Chủ Nhật, 28 tháng 8, 2011

0504-Gastrointestinal Tract and Abdomen

Section 5 Gastrointestinal Tract and Abdomen

4 Intestinal Obstruction
W. Scott Helton, M.D., F.A.C.S.
Professor and Chief, Division of General Surgery, Department of Surgery
University of Illinois at Chicago College of Medicine

Piero M. Fisichella, M.D.
Resident, Department of Surgery
University of Illinois at Chicago College of Medicine



Assessment of Intestinal Obstruction

Intestinal obstruction is a common medical problem and accounts for a large percentage of surgical admissions for acute abdominal pain [see 5:1 Acute Abdominal Pain].1 It develops when air and secretions are prevented from passing aborally as a result of either intrinsic or extrinsic compression (i.e., mechanical obstruction) or gastrointestinal paralysis (i.e., nonmechanical obstruction in the form of ileus or pseudo-obstruction). Small intestinal ileus is the most common form of intestinal obstruction; it occurs after most abdominal operations and is a common response to acute extra-abdominal medical conditions and intra-abdominal inflammatory conditions [see Table 1].2 Mechanical small bowel obstruction is somewhat less common; such obstruction is secondary to intra-abdominal adhesions, hernias, or cancer in about 90% of cases [see Table 2]. Mechanical colonic obstruction accounts for only 10% to 15% of all cases of mechanical obstruction and most often develops in response to obstructing carcinoma, diverticulitis, or volvulus [see Table 3]. Acute colonic pseudo-obstruction occurs most frequently in the postoperative period or in response to another acute medical illness.

There are several different methods of classifying mechanical obstruction: acute versus chronic, partial versus complete, simple versus closed-loop, and gangrenous versus nongangrenous. The importance of these classifications is that the natural history of the condition, its response to treatment, and the associated morbidity and mortality all vary according to which type of obstruction is present.

When chyme and gas can traverse the point of obstruction, obstruction is partial; when this is not the case, obstruction is complete. When the bowel is occluded at a single point along the intestinal tract, leading to intestinal dilatation, hypersecretion, and bacterial overgrowth proximal to the obstruction and decompression distal to the obstruction, simple obstruction is present. When a segment of bowel is occluded at two points along its course by a single constrictive lesion that occludes both the proximal and the distal end of the intestinal loop as well as traps the bowel's mesentery, closed-loop obstruction is present. When the blood supply to a closed-loop segment of bowel becomes compromised, leading to ischemia and eventually to bowel wall necrosis and perforation, strangulation is present. The most common causes of simple obstruction are intra-abdominal adhesions, tumors, and strictures; the most common causes of closed-loop obstruction are hernias, adhesions, and volvulus.

One of the most difficult tasks in general surgery is deciding when to operate on a patient with intestinal obstruction. The purpose of the following discussion is to outline a safe, efficient, and cost-effective stepwise approach to making this often difficult decision and to optimizing the management of patients with this problem. Absolutes are few and far between: treatment must always be highly individualized. Consequently, the following recommendations are intended only as guidelines, not as surgical dicta.

Clinical Evaluation

History and Clinical Setting

When a patient complains of acute obstipation, abdominal pain and distention, nausea, and vomiting, the probability that either mechanical bowel obstruction or ileus is present is very high.3 Mechanical obstruction can often be distinguished from ileus or pseudo-obstruction on the basis of the location, character, and severity of abdominal pain. Pain from mechanical obstruction is usually located in the middle of the abdomen, whereas pain from ileus and pseudo-obstruction is diffuse. Pain from ileus is usually mild, and pain from obstruction is typically more severe. In general, pain increases in severity and depth over time as obstruction progresses; however, in mechanical obstruction, pain severity may decrease over time as a result of bowel fatigue and atony. The periodicity of pain can help localize the level of obstruction: pain from proximal intestinal obstruction has a short periodicity (3 to 4 minutes), and distal small bowel or colonic pain has longer intervals (15 to 20 minutes) between episodes of nausea, cramping, and vomiting.

Abdominal distention, nausea, and vomiting usually develop after pain has already been felt for some time. The patient should be asked what degree of abdominal distention is present and whether there has been a sudden or rapid change. Distention developing over many weeks suggests a chronic process or progressive partial obstruction. Massive abdominal distention coupled with minimal crampy pain, nausea, and vomiting suggests long-standing intermittent mechanical obstruction or some form of chronic intestinal pseudo-obstruction. The combination of a gradual change in bowel habits, progressive abdominal distention, early satiety, mild crampy pain after meals, and weight loss also suggests chronic partial mechanical bowel obstruction. If the patient has undergone evaluation for similar symptoms before, any previous abdominal radiographs or contrast studies should be reviewed. The patient should be asked when flatus was last passed: failure to pass flatus may signal a transition from partial to complete bowel obstruction. Patients with an intestinal stoma (ileostomy or colostomy) who present with signs and symptoms of obstruction often report abdominal distention and pain after a sudden change in stomal output of stool, liquid, or air.

The patient should also be asked about (1) previous episodes of bowel obstruction, (2) previous abdominal or pelvic operations, (3) a history of abdominal cancer, and (4) a history of intra-abdominal inflammation (e.g., inflammatory bowel disease, cholecystitis, pancreatitis, pelvic inflammatory disease, or abdominal trauma). Any of these factors increases the chance that the obstruction is secondary to an adhesion or recurrent cancer. Obstructive symptoms that come and go suddenly over several days in a patient older than 65 years should increase the index of suspicion for gallstone ileus.4 If the patient has experienced episodes of obstruction before, one should ask about the etiology and the response to treatment. If the patient has ever undergone an abdominal operation, one should try to obtain and read the operative report, which can provide a great deal of helpful information (e.g., description of adhesions, assessment of their severity, and evaluation of intra-abdominal pathology and anatomy). If abdominal cancer was present, one should find out what operation was performed and attempt to determine the likelihood of intra-abdominal recurrence.

The clinical setting often provides clues to the cause and type of bowel obstruction. In hospitalized patients, there is likely to be an associated medical condition or metabolic derangement that led to obstruction. A thorough review of the patient's medical history and hospital course should be undertaken to identify precipitating events that could have led to intestinal obstipation. One should ask the patient about any previous abdominal irradiation and should note and take into account all medications the patient is taking, especially anticoagulants and agents with anticholinergic side effects. Patients who are receiving chemotherapy or have undergone abdominal radiation therapy are prone to ileus. Severe infection, fluid and electrolyte imbalances, narcotic and anticholinergic medications, and intra-abdominal inflammation of any origin may be implicated. Acute massive abdominal distention in a hospitalized patient usually results from acute gastric distention, small bowel ileus, or acute colonic pseudo-obstruction. Excessive anticoagulation can lead to retroperitoneal, intra-abdominal, or intramural hematoma that can cause mechanical obstruction or ileus. Finally, there are specific problems that tend to arise in the postoperative period; these are discussed more fully elsewhere [see Urgent Operation, Early Postoperative Technical Complications, and No Operation, Early Postoperative Obstruction, below].

Physical Examination and Resuscitation

The initial steps in the physical examination are (1) developing a gestalt of the patient's illness and (2) assessing the patient's vital signs, hydration status, and cardiopulmonary system. A nasogastric tube, a Foley catheter, and an I.V. line are placed immediately while the physical examination is in progress. The volume and character of the gastric aspirate and urine are noted. A clear, gastric effluent is suggestive of gastric outlet obstruction. A bilious, nonfeculent aspirate is a typical sign of medial to proximal small bowel obstruction or colonic obstruction with a competent ileocecal valve. A feculent aspirate is a typical sign of distal small bowel obstruction. Volume replacement, if necessary, is initiated with isotonic saline solution or lactated Ringer solution. Urine output must be adequate (at least 0.5 ml/kg/hr) before the patient can be taken to the OR; supplemental potassium chloride (40 mEq/L) is administered once this is achieved.

Fever may be present, suggesting that the obstruction may be a manifestation of an intra-abdominal abscess. Signs of pneumonia or myocardial infarction should be sought: these conditions, like intestinal obstruction, can have upper abdominal pain, distention, nausea, and vomiting as presenting symptoms. Dyspnea and labored breathing may occur secondary to severe abdominal distention or pain, in which case immediate relief should be provided by placing the patient in the lateral decubitus position and offering narcotics as soon as the initial physical examination is performed. Jaundice raises the possibility of gallstone ileus or metastatic cancer.

Examination of the abdomen proceeds in an orderly manner from observation to auscultation to palpation and percussion. The patient is placed in the supine position with the legs flexed at the hip to decrease tension on the rectus muscles. The degree of abdominal distention observed varies, depending on the level of obstruction: proximal obstructions may cause little or no distention. Abdominal scars should be noted. Abdominal asymmetry or a protruding mass suggests an underlying malignancy, an abscess, or closed-loop obstruction. The abdominal wall should be observed for evidence of peristaltic waves, which are indicative of acute small bowel obstruction.

Auscultation should be performed for at least 3 to 4 minutes to determine the presence and quality of bowel sounds. High-pitched bowel tones, tingles, and rushes are suggestive of an obstructive process, especially when temporally associated with waves of crampy pain, nausea, or vomiting. The absence of bowel tones is typical of intestinal paralysis but may also indicate intestinal fatigue from long-standing obstruction, closed-loop obstruction, or pseudo-obstruction.

Approximately 70% of patients with bowel obstruction have symmetrical tenderness, whereas fewer than 50% have rebound tenderness, guarding, or rigidity.3 The traditional teaching is that localized tenderness and guarding indicate underlying strangulated bowel; however, prospective studies have demonstrated that these physical findings are neither specific nor sensitive for detecting underlying strangulation5 or even obstruction.3 Nevertheless, most surgeons still believe that guarding, rebound tenderness, and localized tenderness reflect underlying strangulation and therefore are indications for operation. Patients with ileus tend to have generalized abdominal tenderness that cannot be distinguished from the tenderness of mechanical obstruction. Gentle percussion is performed over all quadrants of the abdomen to search for areas of dullness (suggestive of an underlying mass), tympany (suggestive of underlying distended bowel), and peritoneal irritation.

A thorough search is made for inguinal, femoral, umbilical, and incisional hernias. The rectum is examined for masses, fecal impaction, and occult blood. If the patient has an ileostomy or a colostomy, the stoma is examined digitally to make sure that there is no obstruction at the level of the fascia.

Investigative Studies

Imaging

One should obtain a chest x-ray in all patients with bowel obstruction to exclude a pneumonic process and to look for subdiaphragmatic air. In most cases, supine, upright, or lateral decubitus films of the abdomen can distinguish the type of obstruction present (mechanical or nonmechanical, partial or complete) and establish the location of the obstruction (stomach, small bowel, or colon). A useful technique for evaluating abdominal radiographs is to look systematically for intestinal gas along the normal route of the GI tract, beginning at the stomach, continuing through the small bowel, and, finally, following the course of the colon to the rectum. The following questions should be kept in mind as this is done.

Figure 1. Supine radiograph: complete small bowel obstruction
Figure 2. Radiograph: acute colonic pseudo-obstruction
Figure 3. Radiograph: postoperative ileus

It is important to be able to distinguish between small and large bowel gas. Gas in a distended small bowel outlines the valvulae conniventes, which traverse the entire diameter of the bowel lumen [see Figure 1]. Gas in a distended colon, on the other hand, outlines the colonic haustral markings, which cross only part of the bowel lumen and typically interdigitate [see Figures 2 and 3]. Distended small bowel loops usually occupy the central abdomen [see Figure 1], whereas distended large bowel loops are typically seen around the periphery [see Figure 2]. In patients with ileus, distention usually extends uniformly throughout the stomach, the small bowel, and the colon [see Figure 3], and air-fluid levels may be found in the colon and the small intestine.

Figure 4. Upright radiograph: complete small bowel obstruction

Patients with gastric outlet obstruction or gastric atony typically have a giant gastric bubble if no nasogastric tube has been placed, with little or no air in the small bowel or the colon. Patients with mechanical small bowel obstruction usually have multiple air-fluid levels, with distended bowel loops of varying sizes arranged in an inverted U configuration [see Figure 4]. A dilated loop of small bowel appearing in the same location on supine and upright films suggests obstruction of a fixed segment of bowel by an adhesion or an internal hernia [see Figures 1 and 4]. Small bowel obstruction is often accompanied by a paucity of gas in the colon. The complete absence of colonic gas is strongly suggestive of complete small bowel obstruction; however, the presence of colonic gas does not exclude complete small bowel obstruction, in that there may have been unevacuated gas distal to a point of complete obstruction before the radiograph was taken. On the other hand, if repeat radiographs demonstrate decreased or absent colonic or rectal gas in a patient with small bowel obstruction who previously had more colonic or rectal gas, it is probable that partial obstruction has become complete, and immediate operation is almost always indicated. High-grade obstruction of the colon with an incompetent ileocecal valve may manifest itself as distended small bowel loops with air-fluid levels, thereby mimicking small bowel obstruction. Hence, it is sometimes necessary to perform a barium enema to exclude colonic obstruction.

Figure 5a. X-ray: massive sigmoid volvulus
Figure 5b. Barium enema: massive sigmoid volvulus
Figure 6a. Radiograph: cecal volvulus
Figure 6b. Barium enema: cecal volvulus
Figure 7. Radiograph: complete colonic obstruction

Massive gaseous distention of the colon is usually secondary to distal colonic or rectal obstruction, volvulus, or pseudo-obstruction [see Figures 2, 5a, 5b, 6a, 6b, and7]. There are well-defined radiographic criteria that are highly sensitive and specific for sigmoid volvulus.6 If there is any uncertainty regarding the presence, type, or level of colonic obstruction, immediate sigmoidoscopy followed by barium enema is diagnostic.

Laboratory Tests

Serum electrolyte concentrations, the hematocrit, the serum creatinine concentration, and the coagulation profile (prothrombin time [or international normalized ratio—INR] and platelet count) are helpful in determining the severity of volume depletion and guiding resuscitative efforts. If ileus is suspected, serum magnesium and calcium levels should be measured, and urinalysis should be done to check for hematuria.

Determination of Need for Operation and Classification of Obstruction

The combination of a thorough history, a carefully performed physical examination, and correctly interpreted abdominal radiographs usually allows one to identify the type of bowel obstruction present and to decide whether a patient requires immediate, urgent, or delayed operation [see Table 4] or can safely be treated initially with nonoperative measures. To this end, it is particularly important and useful to stratify patients into those with mechanical obstruction and those with nonmechanical obstruction. In patients with mechanical bowel obstruction, an effort should be made to determine whether the obstruction is complete or partial. Except for a few clinical situations, patients with complete bowel obstruction require immediate operation; conversely, patients with partial bowel obstruction rarely do. Finally, an effort should be made to establish the level and cause of obstruction because these factors often help guide therapy and affect the probability of success in response to specific therapeutic intervention. Patients with nonmechanical obstruction, which derives from ileus or pseudo-obstruction [see Ileusand Pseudo-obstruction, below], do not require immediate operation.

Adjunctive Tests for Equivocal Situations

Sigmoidoscopy

When one is uncertain whether the obstruction is mechanical or not on the basis of the information in hand, additional diagnostic measures are immediately indicated. When large amounts of colonic air extend down to the rectum, flexible or rigid sigmoidoscopy will readily exclude a rectal or distal sigmoid obstruction. Care must be exercised to avoid insufflating large amounts of air during endoscopy: excessive insufflation can cause overdistention of the colon above the level of the possible obstruction, which can be counterproductive and harmful. If sigmoidoscopy yields normal findings but partial colonic obstruction seems to be the correct diagnosis, a water-soluble contrast enema should be administered.7 Barium studies may be harmful in patients with acute obstruction when they are performed before the nature of the obstruction (complete or partial) is determined. Abdominal ultrasonography, though not as definitive as a contrast examination, is also able to diagnose suspected colonic obstruction in 85% of patients.8

Ultrasonography, Computed Tomography, and Fast Magnetic Resonance Imaging

Abdominal radiographs can be entirely normal in patients with complete, closed-loop, or strangulation obstruction.9 Therefore, if the patient's clinical profile and the results of physical examination are consistent with intestinal obstruction despite normal abdominal radiographs, abdominal ultrasonography, CT scanning, or fast MRI should be performed immediately.9–18 All three modalities are highly sensitive and specific for intestinal obstruction when performed properly and interpreted by experienced clinicians. Two prospective clinical trials found ultrasonography to be as sensitive as and more specific than abdominal radiography in diagnosing intestinal obstruction.19,20 Ultrasonography, CT, and fast MRI are all capable of detecting the cause of the obstruction, as well as the presence of closed-loop or strangulation obstruction.8,10,15–18,21–24

Sonographic criteria have been established for small bowel and colonic obstruction8,21,22: (1) simultaneous observation of distended and collapsed bowel segments, (2) free peritoneal fluid, (3) inspissated intestinal contents, (4) paradoxical pendulating peristalsis, (5) highly reflective fluid within the bowel lumen, (6) bowel wall edema between serosa and mucosa, and (7) a fixed mass of aperistaltic, fluid-filled, dilated intestinal loops. One group of authors has recommended that when abdominal radiographs are inconclusive or normal in patients with suspected colonic obstruction, ultrasonography, rather than CT or barium enema, should be the next diagnostic step.8 Ultrasonography is well suited to critically ill patients: because it can be performed at the bedside, the risk associated with transport to the radiology suite is avoided. Given that ultrasonography is relatively inexpensive, is easy and quick to perform, and often can provide a great deal of information about the location, nature, and severity of the obstruction, it should be employed early on in the evaluation of all patients with intestinal obstruction.19

Figure 8. CT Scan: partial small bowel obstruction
Figure 9. CT scan: adhesive partial small bowel obstruction
Figure 10. CT scan: partial small bowel obstruction
Figure 11. CT scan: early closed-loop small bowel obstruction

Several authors have recommended that patients with suspected small bowel obstruction and equivocal plain abdominal films undergo CT scanning before a small bowel contrast series is ordered.11–14 CT scanning has several advantages over a small bowel contrast examination in this setting: (1) it can ascertain the level of obstruction, (2) it can assess the severity of the obstruction and determine its cause, and (3) it can detect closed-loop obstruction and early strangulation [see Figures 8, 9, 10, and 11]. CT can also detect inflammatory or neoplastic processes both outside and inside the peritoneal cavity and can visualize small amounts of intraperitoneal air or pneumatosis cystoides intestinalis not seen on conventional films [see Figure 10]. Prospective studies have demonstrated that the accuracy of CT in diagnosing bowel obstruction is higher than 95% and that its sensitivity and specificity are each higher than 94%.23,24 CT scanning distinguishes colonic mechanical obstruction from pseudo-obstruction more accurately than conventional films do and thus is the preferred modality in many cases.25

There is evidence to indicate that fast MRI with T2-weighted images is more sensitive, specific, and accurate than contrast-enhanced helical CT scanning in establishing the location and cause of bowel obstruction.17 The advantages of fast MRI over helical CT scanning are (1) that the image acquisition time is short (1 to 2 seconds per slice), which means that the image can be acquired in the space of a single held breath, and (2) that no contrast agents are required. In addition, because of its multiplanar capability, MRI is also more effective at demonstrating the transition point of the obstruction. When helical CT scanning is nondiagnostic in a patient with suspected bowel obstruction and fast MRI is not available, a small bowel follow-through examination with dilute barium is often useful.14

Contrast Studies

Enteroclysis (direct injection of BaSO4 into the small bowel) is generally considered the most sensitive method of distinguishing between ileus and partial mechanical small bowel obstruction: it has a diagnostic sensitivity of 87% for adhesive obstruction.26,27 Many surgeons are concerned that injection of barium might cause partial obstruction to progress to complete obstruction; however, there is no evidence that this ever occurs, and one therefore should not refrain from using barium to diagnose partial small bowel obstruction.28–31 If complete obstruction is identified, the patient should undergo immediate operation. If partial obstruction is identified in either the small or the large bowel, the patient is treated accordingly. If (1) mechanical obstruction is not identified and (2) a point of obstruction, as evidenced by the finding of both dilated and decompressed intestinal loops, cannot be identified through abdominal ultrasonography, CT scanning, or fast MRI, then the diagnosis is almost certainly ileus, in which case one's attention is directed toward identifying and correcting the underlying precipitating cause [see Table 1] and [see Mechanical Obstruction, No Operation, Adhesive Partial Small Bowel Obstruction, below].

Mechanical Obstruction

Terminal Illness

Patients with a terminal illness (e.g., AIDS or advanced carcinomatosis) to whom surgical treatment offers little hope of improved quality or duration of life may choose not to undergo operative intervention for acute bowel obstruction. These patients should be offered comfort measures, including continuous morphine infusion, rehydration, and administration of antisecretory agents.32–34 In some of these patients, endoscopic deployment of plastic stents may relieve high-grade partial obstruction, thus rendering laparotomy unnecessary.35,36 Patients who do not wish to die of malignant bowel obstruction in a hospital should be offered hospice care or home visiting nurse services with continuous octreotide infusion, I.V. rehydration, and gastrostomy decompression.37,38 Three prospective, randomized clinical trials demonstrated that octreotide significantly attenuated the severity of nausea and vomiting and the degree of subjective discomfort in patients with inoperable obstruction and permitted the discontinuance of nasogastric tube decompression.33,34,39 One of these studies also demonstrated that octreotide significantly reduced the degree of fatigue and anorexia experienced.39 When long-term gastric decompression is required for palliation in a terminally ill patient, percutaneous endoscopic gastrostomy or jejunostomy should be considered [see 5:18 Gastrointestinal Endoscopy].40 Attention must always be paid to quality-of-life issues and to the patient's potential interest in pursuing nonoperative forms of palliation. For many terminally ill or incurable patients with bowel obstruction, the most humane and sensible treatment comprises nothing more than instituting palliative measures such as those described.

Immediate Operation

All patients with complete bowel obstruction, whether of the small intestine or the large, should undergo immediate operation unless extraordinary circumstances (e.g., diffuse carcinomatosis, terminal illness, or sigmoid volvulus that responds to sigmoidoscopic decompression) are present. If one attempts to manage complete intestinal obstruction nonoperatively, one risks delaying definitive treatment of patients with intestinal ischemia and subjecting them to significantly increased morbidity and mortality should perforation or severe infection develop.5,41

Immediate operation is also indicated when bowel obstruction is associated with peritonitis; incarcerated strangulated hernias; suspected or confirmed strangulation; pneumatosis cystoides intestinalis; sigmoid volvulus accompanied by systemic toxicity or peritoneal irritation; colonic volvulus above the sigmoid colon; or fecal impaction. These conditions will not resolve without operation and are associated with increased morbidity, mortality, and cost if diagnosis and treatment are delayed. The only time one would not operate immediately on any patient with one of these diagnoses is when the patient requires cardiopulmonary stabilization, additional resuscitation, or both. Whenever there is any doubt as to the presence of any of these conditions, additional diagnostic tests (e.g., ultrasonography, CT, fast MRI, or contrast studies) are indicated to confirm or exclude them.

Strangulation and Closed-Loop Obstruction

Morbidity and mortality from intestinal obstruction vary significantly and depend primarily on the presence of strangulation and subsequent infection. Strangulation obstruction occurs in approximately 10% of all patients with small intestinal obstruction. It carries a mortality of 10% to 37%, whereas simple obstruction carries a mortality of less than 5%.5,28,42,43 Early recognition and immediate operative treatment of strangulation obstruction are the only current means of decreasing this mortality. Strangulation obstruction occurs most frequently in patients with incarcerated hernias, closed-loop obstruction, volvulus, or complete bowel obstruction; hence, identification of any of these specific causes of obstruction is an important and clear indication for immediate operation. Radiographic evidence of pneumatosis cystoides intestinalis or free intraperitoneal air in a patient with a clinical picture of bowel obstruction is indicative of strangulation, perforation, or both and constitutes an indication for operation. High-quality abdominal CT with I.V. contrast can detect advanced strangulation and identify early, reversible strangulation [see Figure 11].13,15,16

Abdominal ultrasonography can also identify edematous, hemorrhagic loops of intestine. Accordingly, whenever one is concerned about possible strangulation or closed-loop obstruction but is not yet committed to taking the patient immediately to the OR, an ultrasonogram or a CT scan should be obtained. In fact, given that ultrasonography, CT, and fast MRI are the only well-established means of diagnosing strangulation obstruction short of exploratory laparotomy or laparoscopy, an argument can be made that one of these modalities should be performed in all patients who have been admitted to the hospital with bowel obstruction and are initially being treated nonoperatively.

Many surgeons base the decision whether to operate on patients with bowel obstruction on the presence or absence of the so-called classic signs of strangulation obstruction—continuous abdominal pain, fever, tachycardia, peritoneal signs, and leukocytosis—and on their clinical experience. Unfortunately, these classically taught signs, even in conjunction with abdominal x-rays and clinical judgment, are incapable of reliably detecting closed-loop or gangrenous bowel obstruction.5,28,41,44 In fact, one prospective clinical trial concluded that the five classic signs of strangulation obstruction and experienced clinical judgment were not sensitive for, specific for, or predictive of strangulation5: in more than 50% of the patients who had intestinal strangulation, the condition was not recognized preoperatively. Such findings suggest that early nonoperative recognition of intestinal strangulation is not feasible without ultrasonography, CT, or fast MRI.

Incarcerated or Strangulated Hernias

A hernia that is incarcerated, tender, erythematous, warm, or edematous is an indication for immediate operation. Primary or incisional hernias may not be palpable in obese patients, in which case ultrasonography, CT scanning, or fast MRI should be performed.

Nonsigmoid Volvulus and Sigmoid Volvulus with Systemic Toxicity or Peritoneal Signs

All intestinal volvuli are closed-loop obstructions and thus carry a high risk of intestinal strangulation, infarction, and perforation. Patients typically present with acute, colicky abdominal pain, massive distention, nausea, and vomiting. Sigmoid volvulus is the most common form of colonic volvulus, followed by cecal volvulus. Abdominal radiographs are fairly diagnostic for colonic volvulus [see Figures 5a, 5b, and 6aand6b]. In contrast, small bowel volvulus may not be visualized on plain radiographs, because the closed loop fills completely with fluid and no air-fluid level can be seen. Small bowel volvulus is readily detected by ultrasonography or CT scanning; one or both of these procedures should be performed in patients presenting with signs and symptoms of bowel obstruction and normal abdominal radiographs. Small bowel volvulus is an indication for immediate operation.

If one observes signs of systemic toxicity, a bloody rectal discharge, fever, leukocytosis, or peritoneal irritation in a patient with sigmoid volvulus, the patient should undergo immediate operation; if all of these signs are absent, the patient should undergo sigmoidoscopy. When there are no signs of peritonitis or generalized toxicity, sigmoidoscopic decompression is safe and effective in more than 95% of patients with sigmoid volvulus.45 If mucosal gangrene or a bloody effluent is noted at the time of sigmoidoscopy, immediate operative intervention is necessary even in the absence of any clinical signs or symptoms of strangulation. After sigmoidoscopy, the patient can undergo elective bowel preparation and a single-stage sigmoid resection before being discharged from the hospital. If, however, clinical toxicity, a bloody rectal discharge, fever, or peritoneal irritation arises at any time after sigmoidoscopic decompression while the patient is being prepared for an elective procedure, immediate operation is indicated.

Patients with volvulus proximal to the sigmoid colon should undergo immediate operation regardless of whether peritoneal irritation is present. The incidence of strangulation infarction is high in such patients, and nonoperative therapy often fails. If the diagnosis of nonsigmoid colonic volvulus is in doubt, a barium enema is indicated to exclude colonic pseudo-obstruction.

Fecal Impaction

Complete colonic obstruction secondary to fecal impaction in the rectum can sometimes be successfully relieved through disimpaction at the bedside; however, this can be difficult and extremely uncomfortable for the patient. The most expeditious and successful method of relieving the obstruction is to disimpact the patient while he or she is under general or spinal anesthesia. In one study, the pulsed-irrigated enhanced-evacuation (PIEE) procedure, which can be performed at the bedside, successfully resolved fecal impaction in approximately 75% of geriatric patients.46 In another study, administration of a polyethylene glycol 3350 solution over 3 days successfully resolved intestinal obstruction from fecal impaction in 75% of pediatric patients.47

Urgent Operation

Lack of Response to Nonoperative Therapy within 24 to 48 Hours

It is usually safe to manage partial bowel obstruction initially by nonoperative means: a nihil per os (NPO) regimen, nasogastric decompression, analgesics, and octreotide. Such therapy is successful in most cases, especially if the cause of obstruction is postoperative adhesions, but there is always the risk that complete bowel obstruction or strangulation already exists but is undetected. Furthermore, there is the risk that while the patient is being observed, partial obstruction will progress to complete obstruction or strangulation and perforation will develop. It is therefore crucial to be alert to changes in the patient's condition.

Repeated examination of the abdomen by the same clinician is the most sensitive way of detecting progressive obstruction. Examinations should be performed no less frequently than every 3 hours. If abdominal pain, tenderness, or distention increases or the gastric aspirate changes from nonfeculent to feculent, abdominal exploration is usually indicated. Abdominal radiographs should be repeated every 6 hours after nasogastric decompression and reviewed by the surgeon who is following the patient. If proximal small bowel distention increases or distal intestinal gas decreases, nonoperative therapy is less likely to be successful; in these circumstances, early operative intervention should be seriously considered. Conversely, if the patient's condition appears stable or improved and x-rays indicate that the obstruction either has resolved somewhat or at least is no worse, it is generally safe to continue nonoperative care for another 12 to 24 hours. If the clinical picture is stable after 24 hours of observation, one must decide whether to operate or to continue nonoperative therapy. Clinical judgment and experience, coupled with thorough and accurate assessment of the patient's underlying diagnosis and clinical condition, have traditionally been the most reliable guides for making this decision. Currently, however, it appears that the decision whether to operate can be made more cost-effectively and reliably on the basis of abdominal imaging studies [see No Operation, Adhesive Partial Small Bowel Obstruction, below].

Early Postoperative Technical Complications

When normal bowel function initially returns after an abdominal operation but then is replaced by a clinical picture suggestive of early postoperative mechanical obstruction, the explanation may be a technical complication of the operation (e.g., phlegmon, abscess, intussusception, a narrow anastomosis, an internal hernia, or obstruction at the level of a stoma). An early, aggressive diagnostic workup should be performed to identify or exclude these problems because they are unlikely to respond to nasogastric decompression or other forms of conservative management. It is critical to know exactly what was done within the abdomen in the course of the operation. To this end, one should try to speak directly with the operating surgeon rather than attempt to deduce the needed information from the operative report.

If the patient had peritonitis or a colonic anastomosis at the initial operation, one should order a CT scan to look for an intra-abdominal abscess. An abscess or a phlegmon at the site of an anastomosis is usually secondary to anastomotic leakage and is an indication for reoperation. CT scanning can also identify intra-abdominal hematomas, which should be evacuated through early reoperation. In patients recovering from a proctectomy, herniation of the small bowel through a defect in the pelvic floor is a common cause of intestinal obstruction. Oral contrast studies can help identify patients with an internal hernia, intussusception, or anastomotic obstruction and should be performed after the CT scan. A retrograde barium examination should be performed in patients thought to have a problem related to a stoma or an intestinal anastomosis. When none of the above factors appears to be the cause of the postoperative obstruction, it is reasonable for the surgeon to assume that the obstruction is secondary to postoperative adhesions, which are best treated conservatively (see below).

No Operation

In selected patients, nonoperative management of partial small bowel obstruction is highly successful and carries an acceptably low mortality. Such patients include those whose partial obstruction is secondary to intra-abdominal adhesions, occurs in the immediate postoperative period, or derives from an inflammatory condition (e.g., inflammatory bowel disease, radiation enteritis, or diverticulitis).

Adhesive Partial Small Bowel Obstruction

Adhesions are the major cause of bowel obstruction. Obstruction resulting from adhesions can occur as early as 1 month or as late as 20 years after operation.48 Adhesive partial small bowel obstruction is treated initially with nasogastric decompression, I.V. rehydration, and analgesia. Parenteral nutrition should be begun if one believes that oral or enteral nutrition will not be adequate within 5 days. Nonoperative therapy leads to resolution of adhesive partial obstruction in as many as 90% of patients49,50; however, such resolution is followed by recurrence of obstruction in approximately 50% of cases.51,52 When operative adhesiolysis is performed, the mortality is less than 5% for patients with simple obstruction but may be as high as 30% for patients with strangulation or necrotic bowel necessitating intestinal resection.48 In view of this substantial difference in mortality, it is extremely important to be able to confidently distinguish obstruction that is likely to resolve with nonoperative treatment from obstruction that is not. Patients with adhesive partial obstruction that can be accurately predicted to resolve with medical therapy can and should be treated nonoperatively.

Some studies suggest that the nature of the previous abdominal operation or the type of adhesions present may influence the probability that the obstruction will not respond to medical therapy.53–57 Operations associated with a lower likelihood of response to medical therapy include those performed through a midline incision; those involving the aorta, the colon, the rectum, the appendix, or the pelvic adnexa; and those done to relieve previous carcinomatous obstruction. Matted adhesions, which are more common in patients who have undergone midline incisions or colorectal procedures, are less amenable to conservative management than a simple obstructive band is.53 In the context of this kind of operative history, strong consideration should be given to surgical intervention if the obstruction does not resolve within 24 hours—unless comorbid medical conditions tip the risk-benefit balance in the direction of nonoperative therapy.

There is an ongoing debate regarding how long patients with partial adhesive obstruction should be treated conservatively. After 48 hours of nonoperative management, the risk of complications increases substantially, and the probability that the obstruction will resolve diminishes.43 Generally, if the obstruction is going to resolve with nonoperative therapy, there will be a fairly prompt response within the first 8 to 12 hours. Therefore, if a patient's condition has deteriorated or has not significantly improved by 12 hours after nasogastric decompression and resuscitation, exploratory laparotomy is advisable. During this observation period, the patient must be constantly reevaluated, ideally by the same examiner. Analgesics can be safely administered, and repeat abdominal examinations should be performed at 3-hour intervals when the influence of narcotics has waned. Repeat abdominal x-rays should be obtained no later than 6 hours after nasogastric decompression, and the pattern of gas distribution should be compared with that seen on the admission films. A decrease in intestinal gas distal to a point of obstruction coupled with an increase in proximal dilatation suggests that the obstruction is worsening; conversely, a decrease in intestinal distention coupled with the appearance of more gas distally in the colon suggests that the obstruction is being reduced. The degree of abdominal distention, the passage of flatus, and the nature of the nasogastric aspirate should be evaluated periodically. If abdominal distention does not decrease or the gastric aspirate changes from bilious to feculent, the patient should be operated on.

Experimental and clinical studies suggest that patients undergoing nonoperative treatment of bowel obstruction may benefit from the administration of somatostatin analogues as a result of the potent effects these substances exert on intestinal sodium, chloride, and water absorption.57 In one study, animals with either complete or closed-loop partial small bowel obstruction were given either long-acting somatostatin or saline; the treatment group had significantly less intestinal distention, less infarction, and longer survival than the control group.57,58 In a prospective, randomized clinical trial evaluating the use of somatostatin in patients who had complete small bowel obstruction without clinical or radiologic evidence of strangulation, the treatment group was less likely to need operation, had less proximal intestinal distention, and exhibited decreased mucosal necrosis proximal to the point of obstruction.59 In other trials, long-acting somatostatin analogues and other nonsecretagogues significantly decreased the amount of gastric contents aspirated and alleviated the symptoms of intestinal obstruction in terminally ill patients with nonoperable malignant disease.32,33,37–40

It should be possible to determine with a high degree of accuracy and safety which patients will require operation for adhesive small bowel obstruction within 24 to 48 hours of admission to the hospital. As a rule, patients with closed-loop or complete bowel obstruction, who require immediate or urgent operation, can be readily identified by means of abdominal CT or MRI.12–14,17,18 For the remaining patients, who have some degree of partial obstruction, the success or failure of conservative management can be predicted with high accuracy by recording the arrival of contrast material (either a water-soluble agent or a mixed barium preparation) in the right colon within a defined time.14,30,60–63 One prospective study documented the arrival of diatrizoate meglumine-diatrizoate sodium in the colon within 24 hours and found this measure to have a sensitivity of 98%, a specificity of 100%, an accuracy of 99%, a positive predictive value of 100%, and a negative predictive value of 96% as a predictor of successful nonoperative treatment.64 Other studies achieved comparable results with shorter arrival times (e.g., 4 or 8 hours).14,61,65

Several prospective, randomized clinical trials have addressed the issue of whether administration of contrast material can itself be therapeutic with respect to resolving adhesive small bowel obstruction. Two such studies examined small bowel follow-through with barium, either alone or mixed with diatrizoate meglumine.30,31 Both found that the intervals between admission and operation were shorter for patients randomized to the contrast arm than for those in the control group but that contrast examination did not lead to more expeditious resolution of obstruction. Both studies also demonstrated that barium could be administered to patients with small bowel obstruction safely and without complications.

Four prospective, randomized trials have investigated the effects of administering water-soluble hyperosmolar contrast agents to patients with small bowel obstruction.60,62,63,66 In one study, administration of 100 ml of diatrizoate meglumine (1,900 mOsm/L) through the nasogastric tube promoted resolution of adhesive partial obstruction and shortened hospital stay but had no effect on whether laparotomy was required.60 No contrast-related complications were observed. In the second study, administration of a different water-soluble hyperosmolar contrast agent, ioxitalamate meglumine (1,500 mOsm/L), had no therapeutic effect on patients with partial small bowel obstruction.66 Again, no contrast-related complications were observed. In the third study, administration of 100 ml of diatrizoate meglumine through the nasogastric tube significantly accelerated the resolution of adhesive partial small bowel obstruction and shortened hospital stay.62 Patients in whom contrast reached the colon within 24 hours were able to tolerate immediate oral feeding. In addition, the time needed to decide on operative adhesiolysis was shorter in patients receiving the contrast agent. In the fourth study, patients whose partial adhesive small bowel obstruction did not resolve after 48 hours either received 100 ml of diatrizoate meglumine or underwent operative adhesiolysis.63 If administration of the contrast agent revealed complete bowel obstruction, operative treatment was immediately initiated. If it revealed partial obstruction, conservative treatment was continued; in 100% of these patients, the obstruction then resolved without operation. No contrast-mediated complications, no bowel strangulation, and no deaths were reported. The significant treatment effect reported in three of the four randomized clinical trials, along with the absence of any deleterious contrast-related complications in all four, constitutes sufficient evidence to support the administration of 100 ml of diatrizoate meglumine to patients with adhesive partial small bowel obstruction.

By accelerating the resolution of partial small bowel obstruction and ileus, administration of water-soluble contrast agents can shorten the expected hospital stay and thereby reduce the cost of care. Thus, it is reasonable that the first step in managing suspected partial small bowel obstruction from adhesions or postoperative ileus should be to administer water-soluble contrast material intragastrically. When bowel function does not return within 24 hours and the obstruction is demonstrated to be partial, continued observation is safe and resolution without operation is still highly probable. Eventually, however, there will be a point beyond which continued observation is no longer cost-effective in comparison with operative adhesiolysis (especially laparoscopic adhesiolysis). Additional prospective trials are necessary to determine precisely how long the waiting period before operative treatment should be.

Laparoscopic adhesiolysis Several clinical reports have demonstrated that laparoscopic adhesiolysis for acute small bowel obstruction is both feasible and safe.67–72 Laparoscopic or laparoscopic-assisted lysis of adhesions relieves bowel obstruction in more than 50% of patients and is associated with lower morbidity, earlier return of bowel function, quicker resumption of normal diet, and a shorter hospital stay than open operative lysis.67–71,73 To minimize the risk for bowel injury at the beginning of the operation, the first trocar is inserted under direct vision by means of an open technique, and the incision is placed well away from any previous scars.74,75

At present, there are no prospective, randomized, controlled clinical trials comparing laparoscopic with open adhesiolysis. Perhaps the best study published to date on this issue is a retrospective, matched-pair analysis that used an intention-to-treat analysis.71 In this study, 52% of the patients in the laparoscopic group underwent conversion to open lysis of adhesions either for completion of adhesiolysis or for management of complications. No perforations or recurrent obstructions were missed. Perforations were more common overall in the laparoscopic group than in the open group, though this difference was largely eliminated when patients from the laparoscopic group who underwent conversion to open lysis were not considered. Patients with two or more previous laparotomies had a higher incidence of intraoperative complications than those with fewer laparotomies. Accordingly, the authors recommended against laparoscopic adhesiolysis in patients with two or more previous laparotomies. The high conversion rate in this study notwithstanding, the laparoscopic group as a whole (including conversions) experienced an overall reduction in postoperative complications.

Another potential advantage of laparoscopic adhesiolysis is that it results in fewer intra-abdominal adhesions than open laparotomy76,77 and thus may reduce the risk of recurrent bowel obstruction. However, one study found that despite a reduction in median length of stay, patients treated laparoscopically were at increased risk for early unplanned reoperation as a consequence of either incomplete relief of obstruction or complications.70 In fact, bowel perforation in the course of laparoscopic adhesiolysis often is not detected during the procedure and presents in a delayed fashion.75 Many such injuries are attributable either to insertion of the initial trocar or to delayed perforation of a thermal injury. When laparoscopic adhesiolysis fails to identify and relieve an obvious point of obstruction or when adhesiolysis is inadequate or unsafe, conversion to an open approach is indicated.

Early Postoperative Obstruction

Early postoperative mechanical small bowel obstruction is not uncommon: it occurs in approximately 10% of patients undergoing abdominal procedures.78 Postoperative bowel obstruction is often difficult to diagnose because it gives rise to many of the same signs and symptoms as postoperative ileus: obstipation, distention, nausea, vomiting, abdominal pain, and altered bowel sounds. In most cases, there are roentgenographic signs indicative of small bowel obstruction rather than ileus; however, in some cases, abdominal x-rays fail to diagnose the obstruction.79 Traditionally, when plain radiographs are equivocal, an upper GI barium study with follow-through views is the next test performed to distinguish ileus from partial or complete small bowel obstruction80; however, such studies may yield the wrong diagnosis in as many as 30% of cases.26,79,81 A number of authorities believe that abdominal ultrasonography is excellent at distinguishing postoperative ileus from mechanical obstruction and recommend that it be done before any contrast study.22

Early postoperative obstruction is caused by adhesions in about 90% of patients.79,82 When there are no signs of toxicity and no acute abdominal signs, such obstruction can usually be managed safely with nasogastric decompression.78,79,81,82 As many as 87% of patients respond to nasogastric suction within 2 weeks. About 70% of the patients who respond to nonoperative treatment do so within 1 week, and an additional 25% respond during the following 7 days. If postoperative obstruction does not resolve in the first 2 weeks, it is unlikely to do so with continued nonoperative therapy, and reoperation is probably indicated79,82; about 25% of patients whose postoperative obstruction was initially treated nonoperatively eventually require reoperation. An exception to this guideline arises in patients known to have severe dense adhesions (sometimes referred to as obliterative peritonitis) in response to multiple sequential laparotomies. These patients may have a combination of mechanical obstruction and diffuse small bowel and colonic ileus. The risk of closed-loop obstruction, volvulus, or strangulation in this group of patients is low. Repeat laparotomies and attempts to lyse adhesions may lead to complications, the development of enterocutaneous fistulae, or exacerbation of the adhesions. Often, the best approach to managing these patients is observation for prolonged periods (i.e., months). Total parenteral nutrition (TPN) is indicated. The addition of octreotide to the TPN solution may be helpful and may make patients more comfortable.

Because the risk of intestinal strangulation in patients with postoperative adhesive obstruction is extremely low (< 1%),79,83 one can generally treat these patients nonoperatively for longer periods. In fact, the conservative approach is often the wise one: reoperation may do more harm than good (e.g., by causing enterotomies and inducing denser adhesions). The traditional indications for operation in patients with early postoperative obstruction include (1) deteriorating clinical status, (2) worsening obstructive symptoms, and (3) failure to respond to nonoperative management within 2 weeks. With the rising cost of hospitalization, it might in fact be more cost-effective to reoperate on patients who have persistent obstruction after 7 days. This speculation would have to be tested by a well-organized cost-benefit study conducted in a prospective fashion.

Some physicians have maintained that long intestinal tubes are beneficial in the management of postoperative bowel obstruction.50 However, there is no convincing evidence that long intestinal tubes are any better for resolving bowel obstruction than conventional nasogastric tubes are. In fact, some authorities have reported that the use of such tubes increases morbidity.28,43,44 One prospective, randomized clinical trial that addressed this issue found no differences between the two types of tube with respect to the percentage of patients who were able to avoid operation, the incidence of complications, the time between admission and operation, or the duration of postoperative ileus.84

Inflammatory Conditions

Partial bowel obstruction secondary to inflammatory bowel disease, radiation enteritis, or diverticulitis usually resolves with nonoperative therapy. Bowel obstruction accompanying an acute exacerbation of Crohn disease usually resolves with nasogastric suction, I.V. antibiotics, and anti-inflammatory agents. If, however, CT scanning detects intra-abdominal abscess, there is evidence of a chronic stricture, or the patient exhibits persistent obstructive symptoms, operation may be necessary. Similarly, bowel obstruction arising from acute enteritis caused by radiation exposure or chemotherapy usually resolves with supportive care. Chronic radiation-induced strictures are problematic; astute clinical judgment must be exercised to determine when operative treatment is the best option.

Patients with acute diverticulitis typically present with a history of altered bowel movements, fever, leukocytosis, localized pain, tenderness, and guarding in the left lower quadrant of the abdomen. Approximately 20% of patients with colonic diverticulitis also present with signs and symptoms of partial colonic obstruction. A CT scan should be obtained early in all patients with diverticulitis to ascertain whether there is a pericolic abscess that could be drained percutaneously.85 Partial colonic obstruction in these patients usually resolves with antibiotic therapy, an NPO regimen, and nasogastric decompression. If obstructive symptoms persist for more than 7 days or if obstructive symptoms from a documented stricture recur, operation is indicated.

Elective Operation

Nontoxic, Nontender Sigmoid Volvulus

Patients with nontoxic, nontender sigmoid volvulus whose bowel obstruction is initially treated successfully with sigmoidoscopic decompression are at risk for recurrent colonic obstruction. Accordingly, these patients should undergo elective sigmoid resection after complete bowel preparation.

Recurrent Adhesive or Stricture-Related Partial Small Bowel Obstruction

Many patients whose adhesive bowel obstruction resolves experience no further obstructive episodes. If a patient does present with recurrent obstruction from presumed adhesions, either a contrast examination of the bowel or CT scanning is indicated to determine whether there is a surgically correctable point of stenosis. A strong argument can be made that non-high-risk patients should undergo elective operation after presenting with their second episode of mechanical obstruction. Similarly, patients with recurrent obstruction from strictures of any sort should undergo elective operation, given that these lesions are unlikely to resolve.

Partial Colonic Obstruction

The most common causes of partial colonic obstruction are colon cancer, strictures, and diverticulitis. Cancer and strictures usually must be managed surgically because they generally go on to cause obstruction later. Strictures from ischemia or endometriosis usually call for elective colonic resection. Inflammatory strictures from diverticulitis may resolve; however, if obstructive symptoms persist or if barium enema examination continues to yield evidence of colonic narrowing, elective resection is warranted.

When abdominal x-rays suggest distal colonic obstruction, digital examination and rigid sigmoidoscopy are performed to exclude fecal impaction, tumors, strictures, and sigmoid volvulus. If obstruction is proximal to the sigmoidoscope, barium contrast examination is indicated. If barium examination does not demonstrate mechanical obstruction, a presumptive diagnosis of colonic pseudo-obstruction is made.

The morbidity and mortality associated with elective colorectal procedures are significantly lower than those associated with emergency colonic surgery. Furthermore, immediate operation for left-side colonic obstruction almost always necessitates the creation of a diverting colostomy. If a colostomy takedown subsequently proves necessary, the overall cost of caring for the patient will be significantly higher than it would have been had a single-stage procedure been performed. For these reasons, one should initially treat partial colonic obstruction with nasogastric suction, enemas, and I.V. rehydration in the hope that the obstruction will resolve and that the patient thus can undergo mechanical and antibiotic bowel preparation and a single-stage procedure comprising resection and primary anastomosis. Patients who do not respond to nonoperative measures within 24 hours should undergo operation within 12 hours with the aim of preventing perforation.

In patients with partially obstructing rectal or distal sigmoid tumors or strictures that can be traversed with a radiologic guide wire, balloon dilatation can be performed and a self-expanding stent deployed.36,86–89 Clinical improvement and resolution of obstruction occur in more than 90% of patients within 96 hours.36,88 With restoration of the bowel lumen, patients can be prepared for elective surgery, can be spared the creation of a diverting colostomy, and can avoid the extra expense and morbidity associated with the performance of two operations.88,89 This approach is also highly successful as primary therapy for bowel obstruction in patients who are not surgical candidates.36 In patients with large, fixed rectal masses, one should obtain CT scans of the pelvis to assess the extent of the tumor. Transrectal laser fulguration and endoluminal stenting are palliative options for restoring bowel lumen patency that may be considered for patients with nonresectable recurrent rectal cancer or radiation strictures in whom operative risk is prohibitively high.

Bowel Obstruction without Previous Abdominal Operation

When partial small bowel obstruction develops and resolves in a patient who has not previously undergone an abdominal operation, a diagnostic workup should be performed to identify the cause of the obstruction; there may be an underlying condition that is likely to cause recurrent obstruction (e.g., an internal hernia, a tumor, malrotation, or metastatic cancer). The first diagnostic test to be ordered should be a CT scan, followed by an upper GI barium study with follow-through views and a barium enema.90 If a pathologic lesion is identified, elective operation is indicated. An argument can be made that no additional diagnostic tests should be performed in these patients and that diagnostic laparoscopy should be performed instead to enable laparoscopic surgery in case a cause of obstruction is identified that can be treated with a minimally invasive procedure. If no cause of obstruction is found at laparoscopy, open laparotomy is performed.

Paraduodenal hernia Paraduodenal hernia, a congenital defect resulting from intestinal malrotation, is probably more common than was once thought. It accounts for approximately 50% of internal hernias. Patients with paraduodenal hernia may present with a catastrophic closed-loop obstruction; more often, however, they exhibit mild, nonspecific GI symptoms such as nausea, vomiting, esophageal reflux, and abdominal pain. Duodenogastric reflux and prominent bile gastritis in the absence of a previous operation or diabetic gastroparesis are indirect signs of a paraduodenal hernia. The diagnosis is established by means of either an upper GI contrast study with small bowel follow-through or CT scanning. When a paraduodenal hernia is identified, operative treatment is indicated. Such treatment is usually successful in alleviating symptoms and preventing strangulation obstruction.91

Nonmechanical Obstruction

Ileus

Figure 12. Approach to management of ileus

Ileus, or intestinal paralysis, is most common after abdominal operations but can also occur in response to any acute medical condition or metabolic derangement [see Table 1]. The pathophysiologic mechanisms that cause ileus are incompletely understood but appear to involve disruption of normal neurohumoral responses.92 Ileus may be classified into two broad categories: postoperative ileus and ileus without antecedent abdominal operation. Postoperative ileus is manifested by atony of the stomach, the small intestine, and the colon and usually resolves spontaneously within a few days as normal bowel motility returns. Typically, the small bowel regains its motility within 24 hours of operation, followed 3 to 4 days later by the stomach and the colon. Initial therapy of ileus is directed at identifying and correcting the presumed cause [see Figure 12]. If the patient experiences abdominal distention, abdominal pain, nausea, or vomiting, then nasogastric decompression, placement of a Foley catheter, and I.V. rehydration are indicated. In postoperative patients, it is best not to use strong narcotics for analgesia and instead to rely on epidural anesthesia and nonsteroidal anti-inflammatory drugs. When ileus develops in patients who have not recently undergone an operation, a thorough history, a careful physical examination, and well-chosen laboratory tests are necessary to identify the possible causes.

When ileus persists for what is, in one's best clinical judgment, an inordinate length of time for the operation performed (typically, longer than 3 to 4 days), the possibility of partial mechanical obstruction, possibly associated with an intra-abdominal abscess or another source of infection, must be considered. If an abscess is suspected, an abdominal CT scan should be obtained. Abdominal ultrasonography has been reported to distinguish postoperative ileus from mechanical obstruction reliably.22 A small bowel contrast examination with barium identifies partial mechanical small bowel obstruction in about 75% of patients.26,28 CT scanning distinguishes ileus from obstruction in about 80% of patients.

Intragastric administration of a water-soluble contrast agent has shown great potential in the treatment of ileus.93,94 In one study, administration of 120 ml of diatrizoate meglumine or diatrizoate sodium via nasogastric tube to 40 adults with postoperative small bowel ileus led to restored intestinal motility within 6 hours in all 40, allowing them to resume oral alimentation within 24 hours.93 Given these results, a prospective, randomized trial that addresses cost-management end points is warranted.

Pseudo-Obstruction

Figure 13. Approach to management of pseudo-obstruction

Pseudo-obstruction [see Figure 13] can exist in the small bowel or the colon and can be either acute or chronic. Acute colonic pseudo-obstruction, also known as Ogilvie syndrome, is the most common form. Colonic pseudo-obstruction occurs most commonly in hospitalized patients in the postoperative period or in response to a nonsurgical acute illness (e.g., pneumonia, myocardial infarction, hypoxia, shock, intestinal ischemia, or electrolyte imbalance). The pathophysiologic mechanisms underlying idiopathic pseudo-obstruction appear to be related to an imbalance in the parasympathetic and sympathetic influences on colonic motility.

The presenting symptoms of acute colonic pseudo-obstruction are massive dilatation of the colon (with the cecum more dilated than the distal colon), crampy pain, nausea, and vomiting.95 If peritoneal irritation or systemic toxicity is present, immediate laparotomy is indicated; if not, treatment involves nasogastric decompression, placement of a rectal tube, tap-water enemas, correction of any underlying metabolic disturbances, and avoidance of narcotic and anticholinergic medications. With conservative management, acute colonic pseudo-obstruction resolves within 4 days in more than 80% of cases.96 Colonoscopy was previously the method of choice for decompression in this setting.97 It has been shown, however, that I.V. administration of neostigmine, 2.5 mg over 2 to 3 minutes, leads to prompt resolution of acute colonic pseudo-obstruction within minutes in nearly all cases.98,99 Now that this previously difficult and potentially lethal problem can readily be treated pharmacologically, colonoscopic decompression and surgical intervention should be reserved for cases in which pharmacologic measures fail.

Chronic intestinal pseudo-obstruction is a rare acquired disorder that is caused by various diseases involving GI smooth muscle, the enteric nervous system, or the extrinsic autonomic nerve supply to the gut.100 These disorders are treated with an NPO regimen, home TPN, and octreotide. Patients with chronic intestinal pseudo-obstruction should be followed closely for long periods and should undergo repeat contrast studies: a condition occasionally develops that can cause mechanical obstruction and that may be surgically correctable.101,102

Cost Considerations

Cost considerations are exerting an ever-growing influence on surgical care in general and on the decision whether to operate in particular. A large percentage of the high total cost of caring for patients with ileus or mechanical intestinal obstruction is accounted for by the cost associated with hospitalization or the need for laparotomy.

Strategies for reducing the overall cost of managing patients with bowel obstruction may take several forms: the development of diagnostic and therapeutic methods that lead to more rapid diagnosis and resolution of ileus and partial small bowel obstruction; the development of techniques for rapid identification of patients with complete or closed-loop obstruction and early reversible strangulation, which would permit earlier operative intervention and thereby reduce the incidence of complications; the development of therapeutic approaches that prevent postoperative ileus; and the development of methods for preventing intra-abdominal adhesions, which would significantly reduce the overall incidence of bowel obstruction. Two prospective, randomized clinical trials demonstrated that placement of a bioresorbable membrane composed of sodium hyaluronate and carboxymethylcellulose underneath abdominal fascial closures significantly reduced the severity and density of postoperative adhesions.103,104 In theory, use of such a product should reduce the incidence of adhesion-related bowel obstruction; however, longer-term studies are required to determine whether this will actually be the case.

From a management viewpoint, if a specific diagnostic test, medication, or approach (e.g., laparoscopy) costs less than a day of hospitalization does, it immediately becomes cost-effective if it reduces complications and shortens length of stay by 1 day. Intragastric administration of a water-soluble contrast agent to relieve small bowel ileus or partial adhesive obstruction is an example of an innovative, cost-effective therapeutic strategy. Diagnostic laparoscopy, abdominal ultrasonography, CT scanning, and fast MRI have all been successfully used to make earlier definitive management decisions and to prevent gangrenous obstruction. Laparoscopic adhesiolysis also leads to earlier hospital discharge. On the basis of the collective experience reported in a substantial number of studies (see above), a logical proposal for cost-effective management of patients with bowel obstruction would be to perform ultrasonography or abdominal CT scanning immediately after initial resuscitation, then to perform laparoscopic surgery on those patients in whom the contrast agent does not arrive in the right colon within 24 hours. However, prospective, randomized clinical trials are needed to evaluate the cost-effectiveness of this and other newer management strategies.

Acknowledgment

Figures 12 and 13 Marcia Kammerer.

References

1. Irvin T: Abdominal pain: a surgical audit of 1190 emergency admissions. Br J Surg 76:1121, 1989 [PMID 2597964]

2. Lucky A, Livingston E, Tache Y: Mechanisms and treatment of postoperative ileus. Arch Surg 138:206, 2003

3. Eskelinen M, Ikonen J, Lipponen P: Contributions of history-taking, physical examination, and computer assistance to diagnosis of acute small-bowel obstruction: a prospective study of 1333 patients with acute abdominal pain. Scand J Gastroenterol 29:715, 1994 [PMID 7973431]

4. Reisner R, Cohen J: Gallstone ileus: a review of 1001 reported cases. Am Surg 60:441, 1994 [PMID 8198337]

5. Sarr M, Bulkley G, Zuidema G: Preoperative recognition of intestinal strangulation obstruction: prospective evaluation of diagnostic capability. Am J Surg 145:176, 1983 [PMID 6849489]

6. Burrell H, Baker D, Wardrop P, et al: Significant plain film findings in sigmoid volvulus. Clin Radiol 49:317, 1994 [PMID 8013194]

7. Fatarr S, Schulman A: Small bowel obstruction masking synchronous large bowel obstruction: a need for emergency barium enema. AJR Am J Roentgenol 140:1159, 1983 [PMID 6602485]

8. Lim J, Ko Y, Lee D, et al: Determining the site and causes of colonic obstruction with sonography. AJR Am J Roentgenol 163:113, 1994 [PMID 8010195]

9. Gough I: Strangulating adhesive small bowel obstruction with normal radiographs. Br J Surg 65:431, 1978 [PMID 656765]

10. Ko Y, Lim J, Le D, et al: Small bowel obstruction: sonographic evaluation. Radiology 188:649, 1993 [PMID 8351327]

11. Balthazar E: For suspected small-bowel obstruction and an equivocal plain film, should we perform CT or a small-bowel series? AJR Am J Roentgenol 163:1260, 1994 [PMID 7976913]

12. Daneshmand S, Hedley C, Stain S: The utility and reliability of computed tomography scan in the diagnosis of small bowel obstruction. Am Surg 65:922, 1999 [PMID 10515535]

13. Donckier V, Closset J, Van Gansbek D, et al: Contribution of computed tomography to decision making in the management of adhesive small bowel obstruction. Br J Surg 85:1071, 1998 [PMID 9717999]

14. Peck J, Milleson T, Phelan J: The role of computed tomography with contrast and small bowel follow-through in management of small bowel obstruction. Am J Surg 177:375, 1999 [PMID 10365873]

15. Zalcman M, Sy M, Donckier V, et al: Helical CT signs in the diagnosis of intestinal ischemia in small-bowel obstruction. AJR Am J Roentgenol 175:1601, 2000 [PMID 11090385]

16. Ha H: CT in the early detection of strangulation in intestinal obstruction. Semin Ultrasound CT MRI 16:141, 1995

17. Beall DP, Fortman BJ, Lawler BC, et al: Imaging bowel obstruction: a comparison between fast magnetic resonance imaging and helical computed tomography. Clin Radiol 57:719, 2002 [PMID 12169282]

18. Matsuoka H, Takahara T, Masaki T, et al: Preoperative evaluation by magnetic resonance imaging in patients with bowel obstruction. Am J Surg 183:614, 2002 [PMID 12095588]

19. Ogata M, Mateer J, Condon R: Prospective evaluation of abdominal sonography for the diagnosis of bowel obstruction. Ann Surg 223:237, 1996 [PMID 8604902]

20. Grunshaw N, Renwick IG, Scarisbrick G, et al: Prospective evaluation of ultrasound in distal ileal and colonic obstruction. Clin Radiol 55:356, 2000 [PMID 10816401]

21. Meiser G, Meissner K: Intermittent incomplete intestinal obstruction: a frequently mistaken identity. Ultrasonographic diagnosis and management. Surg Endosc 3:46, 1989 [PMID 2652354]

22. Meiser G, Meissner K: Ileus and intestinal obstruction—ultrasonographic findings as a guideline to therapy. Hepatogastroenterology 34:194, 1987

23. Megibow A: Bowel obstruction: evaluation with CT. Radiol Clin North Am 32:861, 1994 [PMID 8085000]

24. Balthazar E: CT of small-bowel obstruction. AJR Am J Roentgenol 162:255, 1994 [PMID 8310906]

25. Frager D, Rovno HD, Baer JW, et al: Prospective evaluation of colonic obstruction with computed tomography. Abdom Imaging 23:141, 1998 [PMID 9516501]

26. Dunn JT, Halls JM, Berne TV: Roentgenographic contrast studies in acute small-bowel obstruction. Arch Surg 119:1305, 1984 [PMID 6497637]

27. Caroline DF, Herlinger H, Laufer I, et al: Small bowel enema in the diagnosis of adhesive obstructions. AJR Am J Roentgenol 142:1133, 1984 [PMID 6609596]

28. Brolin R: Partial small bowel obstruction. Surgery 95:145, 1984 [PMID 6695331]

29. Maglinte D, Peterson D, Vahey T, et al: Enteroclysis in partial small bowel obstruction. Am J Surg 147:325, 1984 [PMID 6703203]

30. Anderson C, Humphry W: Contrast radiography in small bowel obstruction: a prospective randomized trial. Mil Med 162:749, 1997 [PMID 9358722]

31. Fevang BT, Jensen D, Fevang J, et al: Upper gastrointestinal contrast study in the management of small bowel obstruction—a prospective randomised study. Eur J Surg 166:39, 2000

32. Muir J, von Gunten C: Antisecretory agents in gastrointestinal obstruction. Clin Geriatr Med 16:327, 2000 [PMID 10783431]

33. Mercadante S, Ripamonti C, Casuccio A, et al: Comparison of octreotide and hyoscine butylbromide in controlling gastrointestinal symptoms due to malignant inoperable bowel obstruction. Support Care Cancer 8:188, 2000 [PMID 10789958]

34. Ripamonti C, Mercadante S, Groff L, et al: Role of octreotide, scopolamine butylbromide, and hydration in symptom control of patients with inoperable bowel obstruction and nasogastric tubes: a prospective randomized trial. J Pain Symptom Manage 19:23, 2000 [PMID 10687323]

35. Matsushita M, Hajiro K, Takukawa H, et al: Plastic prosthesis in the palliation of small bowel stenosis secondary to recurrent gastric cancer: initial cost savings. Gastrointest Endosc 52:571, 2000 [PMID 11023590]

36. de Gregori MA, Mainar A, Tejero E, et al: Acute colorectal obstruction: stent placement for palliative treatment—results of a multicenter study. Radiology 209:117, 1998

37. Khoo D, Hall E, Motson R, et al: Palliation of malignant intestinal obstruction using octreotide. Eur J Cancer 30A:28, 1994 [PMID 7511400]

38. Stiefel F, Morant R: Vapreotide, a new somatostatin analogue in the palliative management of obstructive ileus in advanced cancer. Support Care Cancer 1:57, 1993 [PMID 7511473]

39. Mystakidou K, Tsilika E, Kalaidopoulou O, et al: Comparison of octreotide administration vs. conservative treatment in the management of inoperable bowel obstruction in patients with far advanced cancer: a randomized, double-blind, controlled clinical trial. Anticancer Res 22:1187, 2002 [PMID 12168923]

40. Scheidbach H, Horbach T, Groitl H, et al: Percutaneous endoscopic gastrostomy/jejunostomy (PEG/PEJ) for decompression in the upper gastrointestinal tract. Initial experience with palliative treatment of gastrointestinal obstruction in terminally ill patients with advanced carcinomas. Surg Endosc 13:1103, 1999 [PMID 10556447]

41. Silen W, Hein MF, Goldman L: Strangulation obstruction of the small intestine. Arch Surg 85:137, 1962

42. Laws H, Aldrete J: Small bowel obstruction: a review of 465 cases. South Med J 69:733, 1976 [PMID 935902]

43. Sosa J, Gardner B: Management of patients diagnosed as acute intestinal obstruction secondary to adhesions. Am Surg 59:125, 1993 [PMID 8476142]

44. Snyder EN, McCranie D: Closed loop obstruction of the small bowel. Am J Surg 111:398, 1966 [PMID 5907007]

45. Mangiante E, Croce M, Fabian T, et al: Sigmoid volvulus: a four-decade experience. Am Surg 55:41, 1989 [PMID 2643910]

46. Gilger MA, Wagner ML, Barrish JO, et al: New treatment for rectal impaction in children: an efficacy, comfort, and safety trial of the pulsed-irrigation enhanced-evacuation procedure. J Pediatr Gastroenterol Nutr 18:92, 1994 [PMID 8126626]

47. Youssef NN, Peters JM, Henderson W, et al: Dose response of PEG 3350 for the treatment of childhood fecal impaction. J Pediatr 141:410, 2002 [PMID 12219064]

48. Ellis H: The clinical significance of adhesions: focus on intestinal obstruction. Eur J Surg Suppl 577:5, 1997 [PMID 9076446]

49. Bizer L, Liebling R, Delany H, et al: Small bowel obstruction: the role of non-operative treatment in simple intestinal obstruction and predictive criteria for strangulation obstruction. Surgery 89:407, 1981 [PMID 7209787]

50. Gowen GF: Long tube decompression is successful in 90% of patients with adhesive small bowel obstruction. Am J Surg 185:512, 2003

51. Barkan H, Webster S, Ozeran S: Factors predicting the recurrence of adhesive small-bowel obstruction. Am J Surg 170:361, 1995 [PMID 7573729]

52. Landercasper J, Cogbill TH, Merry WH, et al: Long-term outcome after hospitalization for small-bowel obstruction. Arch Surg 128:765, 1993 [PMID 8317958]

53. Miller G, Boman J, Shrier I, et al: Natural history of patients with adhesive small bowel obstruction. Br J Surg 87:1240, 2000 [PMID 10971435]

54. Ellis H, Moran BJ, Thompson JN, et al: Adhesion-related hospital readmissions after abdominal and pelvic surgery: a retrospective cohort study. Lancet 353:1476, 1999 [PMID 10232313]

55. Parker MC, Ellis H, Moran BJ, et al: Postoperative adhesions: ten-year follow-up of 12,584 patients undergoing lower abdominal surgery. Dis Colon Rectum 44:822, 2001 [PMID 11391142]

56. Meagher AP, Moller C, Hoffmann DC: Non-operative treatment of small bowel obstruction following appendicectomy or operation on the ovary or tube. Br J Surg 80:1310, 1993 [PMID 8242308]

57. Mulvihill S, Pappas T, Fonkalsrud Z, et al: The effect of somatostatin on experimental intestinal obstruction. Ann Surg 207:169, 1988 [PMID 2893593]

58. Gittes G, Nelson M, Debas H, et al: Improvement in survival of mice with proximal small bowel obstruction treated with octreotide. Am J Surg 163:231, 1992 [PMID 1739178]

59. Bastounis E, Hadjinikolaou L, Ioannou N, et al: Somatostatin as adjuvant therapy in the management of obstructive ileus. Hepatogastroenterology 36:538, 1989 [PMID 2575572]

60. Assalia A, Schein M, Kopelman D, et al: Therapeutic effect of oral Gastrografin in adhesive, partial small-bowel obstruction: a prospective randomized trial. Surgery 115:433, 1994 [PMID 8165534]

61. Blackmon S, Lucius C, Wilson JP, et al: The use of water-soluble contrast in evaluating clinically equivocal small bowel obstruction. Am Surg 66:238, 2000 [PMID 10759192]

62. Biondo S, Pares D, Mora L, et al: Randomized clinical study of Gastrografin administration in patients with adhesive small bowel obstruction. Br J Surg 90:542, 2003 [PMID 12734858]

63. Choi H, Chu K, Law W: Therapeutic value of Gastrografin in adhesive small bowel obstruction after unsuccessful conservative treatment, a prospective randomized trial. Ann Surg 223:1, 2002

64. Chen SC, Chang KJ, Lee PH, et al: Oral urografin in postoperative small bowel obstruction. World J Surg 23:1051, 1999 [PMID 10512946]

65. Chen SC, Lin FY, Lee PH, et al: Water-soluble contrast study predicts the need for early surgery in adhesive small bowel obstruction. Br J Surg 85:1692, 1998 [PMID 9876076]

66. Feigin E, Seror D, Szold A, et al: Water-soluble contrast material has no therapeutic effect on postoperative small-bowel obstruction: results of a prospective, randomized clinical trial. Am J Surg 171:227, 1996 [PMID 8619455]

67. Leon EL, Metzger A, Tsiotos GG, et al: Laparoscopic management of small bowel obstruction: indications and outcome. J Gastrointest Surg 2:132, 1998 [PMID 9834408]

68. Strickland P, Lourie DJ, Suddleson EA, et al: Is laparoscopy safe and effective for treatment of acute small-bowel obstruction? Surg Endosc 13:695, 1999 [PMID 10384077]

69. Suter M, Zermatten P, Halkic N, et al: Laparoscopic management of mechanical small bowel obstruction: are there predictors of success or failure? Surg Endosc 14:478, 2000 [PMID 10858476]

70. Bailey IS, Rhodes M, O'Rourke N, et al: Laparoscopic management of acute small bowel obstruction. Br J Surg 85:84, 1998 [PMID 9462391]

71. Wullstein C, Gross E: Laparoscopic compared with conventional treatment of acute adhesive small bowel obstruction. Br J Surg 90:1147, 2003 [PMID 12945085]

72. Fischer CP, Doherty D: Laparoscopic approach to small bowel obstruction. Semin Laparosc Surg 9:40, 2002 [PMID 11979409]

73. Bohm B, Milsom JW, Fazio VW: Postoperative intestinal motility following conventional and laparoscopic intestinal surgery. Arch Surg 130:415, 1995 [PMID 7710343]

74. Vrijland WW, Jeekel J, van Geldorp HJ, et al: Abdominal adhesions, intestinal obstruction, pain, and infertility. Surg Endosc 117:1017, 2003

75. Chapron C, Pierre F, Harchaoui Y, et al: Gastrointestinal injuries during gynaecological laparoscopy. Hum Reprod 14:333, 1999 [PMID 10099974]

76. Garrard CL, Clements RH, Nanney L, et al: Adhesion formation is reduced after laparoscopic surgery. Surg Endosc 13:10, 1999 [PMID 9869679]

77. Tittel A, Treutner KH, Titkova S, et al: Comparison of adhesion reformation after laparoscopic and conventional adhesiolysis in an animal model. Langenbecks Arch Surg 386:141, 2001 [PMID 11374047]

78. Ellozy SH, Harris MT, Bauer JJ, et al: Early postoperative small-bowel obstruction: a prospective evaluation in 242 consecutive abdominal operations. Dis Colon Rectum 45:1214, 2002 [PMID 12352239]

79. Pickleman J, Lee R: The management of patients with suspected early postoperative small bowel obstruction. Ann Surg 212:216, 1989

80. Brolin R: The role of gastrointestinal tube decompression in the treatment of mechanical intestinal obstruction. Am Surg 49:131, 1983 [PMID 6830066]

81. Quatromoni J, Rosoff L, Halls J, et al: Early postoperative small bowel obstruction. Ann Surg 191:72, 1980 [PMID 7352780]

82. Stewart R, Page C, Brender J, et al: The incidence and risk of early postoperative small bowel obstruction. Am J Surg 154:643, 1987 [PMID 3425811]

83. Spears H, Petrelli N, Herrera L, et al: Treatment of small bowel obstruction after colorectal carcinoma. Am J Surg 155:383, 1988 [PMID 3344898]

84. Fleshner PR, Siegman MG, Slater GI, et al: A prospective, randomized trial of short versus long tubes in adhesive small-bowel obstruction. Am J Surg 170:366, 1995 [PMID 7573730]

85. Hulnick D, Megibow A, Balthazar E, et al: Computed tomography in the evaluation of diverticulitis. Radiology 152:491, 1984 [PMID 6739821]

86. Tejero E, Mainar A, Fernández L, et al: New procedure for the treatment of colorectal neoplastic obstructions. Dis Colon Rectum 37:1158, 1994

87. Itabashi M, Hamano K, Kameoka S, et al: Self-expanding stainless steel stent application in rectosigmoid stricture. Dis Colon Rectum 36:508, 1993 [PMID 8482172]

88. Binkert C, Ledermann H, Jost R, et al: Acute colonic obstruction: clinical aspects and cost-effectiveness of preoperative and palliative treatment with self-expanding metallic stents—a preliminary report. Radiology 206:199, 1998

89. Mainar A, DeGregorio Ariza MA, Tejero E, et al: Acute colorectal obstruction: treatment with self-expandable metallic stents before scheduled surgery—results of a multicenter study. Radiology 210:65, 1999

90. Stelmach W, Cass A: Small bowel obstructions: the case for investigation for occult large bowel carcinoma. Aust NZ J Surg 59:181, 1989

91. Yoo HY, Mergelas J, Seibert DG: Paraduodenal hernia: a treatable cause of upper gastrointestinal tract symptoms. Clin Res 31:226, 2000

92. Fromm D: Ileus and obstruction. Surgery: Scientific Principles and Practice. Greenfield LJ, Mulholland MW, Oldham KT, et al, Eds. JB Lippincott Co, Philadelphia, 1993 , p 731

93. Watkins D, Robertson C: Water-soluble radiocontrast material in the treatment of the postoperative ileus. Am J Obstet Gynecol 152:450, 1985 [PMID 4014338]

94. Zer M, Kanzenelson D, Feigenberg Z, et al: The value of Gastrografin in the differential diagnosis of paralytic ileus and mechanical obstruction. Dis Colon Rectum 20:573, 1977 [PMID 578790]

95. Vanek V, Al-Salti M: Acute pseudo-obstruction of the colon (Ogilvie's syndrome): an analysis of 400 cases. Dis Colon Rectum 29:203, 1986 [PMID 3753674]

96. Sloyer A, Panella V, Demas B: Ogilvie's syndrome: successful management with colonoscopy. Dig Dis Sci 33:1391, 1988 [PMID 3180976]

97. Nakhgevany KB: Colonoscopic decompression of the colon in patients with Ogilvie's syndrome. Am J Surg 148:317, 1984 [PMID 6476222]

98. Hutchinson R, Griffiths C: Acute colonic pseudo-obstruction: a pharmacological approach. Ann R Coll Surg Engl 74:364, 1992 [PMID 1416711]

99. Ponec RJ, Saunders MD, Kimmey MB: Neostigmine for the treatment of acute colonic pseudo-obstruction. N Engl J Med 341:137, 1999 [PMID 10403850]

100. Faulk D, Anuras S, Christensen J: Chronic intestinal pseudo-obstruction. Gastroenterology 74:922, 1978 [PMID 346432]

101. Schuffler M, Deitch E: Chronic idiopathic intestinal pseudo-obstruction: a surgical approach. Ann Surg 192:752, 1980 [PMID 7447530]

102. Knoll RF Jr, Schuffler MD, Helton WS: Small bowel resection for relief of chronic intestinal pseudo-obstruction. Am J Gastroenterol 90:1142, 1995 [PMID 7541935]

103. Vrijland WW, Tseng L, Eijkman H, et al: Fewer intraperitoneal adhesions with use of hyaluronic acid-carboxymethylcellulose membrane, a randomized clinical trial. Ann Surg 235:193, 2002 [PMID 11807358]

104. Becker JM, Dayton MT, Fazio VW, et al: Prevention of postoperative abdominal adhesions by a sodium hyaluronate-based bioresorbable membrane: a prospective, randomized, double-blind multicenter study. J Am Coll Surg 183:297, 1996 [PMID 8843257]

What's New ...

Section 5 Gastrointestinal Tract and Abdomen

4 Intestinal Obstruction
W. Scott Helton, M.D., F.A.C.S.
Professor and Chief, Division of General Surgery, Department of Surgery
University of Illinois College of Medicine


Offers a safe, efficient, stepwise approach for deciding whether to operate on a patient with intestinal obstruction and describes the management of patients with this problem. Clinical evaluation, investigative studies, mechanical obstruction, nonmechanical obstruction (including pseudo-obstruction), and cost considerations are described.

To Operate or Not to Operate

The combination of a thorough history, a carefully performed physical examination, and correctly interpreted abdominal radiographs usually allows one to identify the type of bowel obstruction present and to decide whether a patient requires immediate, urgent, or delayed operation [see Table] or can safely be treated initially with nonoperative measures. To this end, it is particularly important and useful to stratify patients into those with mechanical obstruction and those with nonmechanical obstruction. In patients with mechanical bowel obstruction, an effort should be made to determine whether the obstruction is complete or partial. Except for a few clinical situations, patients with complete bowel obstruction require immediate operation; conversely, patients with partial bowel obstruction rarely do. Finally, an effort should be made to establish the level and cause of obstruction, because these factors often help guide therapy and affect the probability of success in response to specific therapeutic intervention. Patients with nonmechanical obstruction, which derives from ileus or pseudo-obstruction, do not require immediate operation.

When one is uncertain whether the obstruction is mechanical or not on the basis of the information at hand, additional diagnostic measures are immediately indicated. When large amounts of colonic air extend down to the rectum, flexible or rigid sigmoidoscopy will readily exclude a rectal or distal sigmoid obstruction. If sigmoidoscopy yields normal findings and if partial colonic obstruction is the most likely diagnosis, a barium enema with water-soluble contrast material should immediately be performed. Abdominal ultrasonography, though not as definitive as a contrast examination, is also able to diagnose suspected colonic obstruction in 85% of patients.

Abdominal radiographs can be entirely normal in patients with complete, closed-loop, or strangulation obstruction. Therefore, if the patient's clinical profile and the results of physical examination are consistent with intestinal obstruction despite normal abdominal radiographs, abdominal ultrasonography, CT scanning, or fast MRI should be performed immediately.1–3 All three modalities are highly sensitive and specific for intestinal obstruction when performed properly and interpreted by experienced clinicians.

1. Zalcman M, Sy M, Donckier V, et al: Helical CT signs in the diagnosis of intestinal ischemia in small-bowel obstruction. AJR Am J Roentgenol 175:1601, 2000 [PMID 11090385]

2. Beall DP, Fortman BJ, Lawler BC, et al: Imaging bowel obstruction: a comparison between fast magnetic resonance imaging and helical computed tomography. Clin Radiol 57:719, 2002 [PMID 12169282]

3. Matsuoka H, Takahara T, Masaki T, et al: Preoperative evaluation by magnetic resonance imaging in patients with bowel obstruction. Am J Surg 183:614, 2002 [PMID 12095588]

Indications for Immediate Operation

All patients with complete bowel obstruction, whether of the small intestine or the large, should undergo immediate operation unless extraordinary circumstances (e.g., diffuse carcinomatosis, terminal illness, or sigmoid volvulus that responds to sigmoidoscopic decompression) are present. If one attempts to manage complete intestinal obstruction nonoperatively, one risks delaying definitive treatment of patients with intestinal ischemia and subjecting them to significantly increased morbidity and mortality should perforation or severe infection develop.

Immediate operation is also indicated when bowel obstruction is associated with peritonitis; incarcerated strangulated hernias; suspected or confirmed strangulation; pneumatosis cystoides intestinalis; sigmoid volvulus accompanied by systemic toxicity or peritoneal irritation; colonic volvulus above the sigmoid colon; or fecal impaction. These conditions will not resolve without operation and are associated with increased morbidity, mortality, and cost if diagnosis and treatment are delayed. The only time one would not operate immediately on any patient with one of these diagnoses is when the patient requires cardiopulmonary stabilization, additional resuscitation, or both. Whenever there is any doubt as to the presence of any of these conditions, additional diagnostic tests (e.g., ultrasonography, CT, or contrast studies) are indicated to confirm or exclude them.

The Role of Laparoscopic Adhesiolysis

Several clinical reports have demonstrated that laparoscopic adhesiolysis for acute small bowel obstruction is both feasible and safe.1,2 Laparoscopic or laparoscopic-assisted lysis of adhesions relieves bowel obstruction in more than 50% of patients and is associated with lower morbidity, earlier return of bowel function, quicker resumption ofnormal diet, and a shorter hospital stay than open operative lysis.1 To minimize the risk of bowel injury at the beginning of the operation, the first trocar is inserted under direct vision by means of an open technique, and the incision is placed well away from any previous scars.3

At present, there are no prospective, randomized, controlled clinical trials comparing laparoscopic with open adhesiolysis. Perhaps the best study published to date on this issue is a retrospective, matched-pair analysis from 2003 that used an intention-to-treat analysis.1 In this study, 52% of the patients in the laparoscopic group underwent conversion to open lysis of adhesions either for completion of adhesiolysis or for management of complications. No perforations or recurrent obstructions were missed. Perforations were more common overall in the laparoscopic group than in the open group, though this difference was largely eliminated when patients from the laparoscopic group who underwent conversion to open lysis were not considered. Patients with two or more previous laparotomies had a higher incidence of intraoperative complications than those with fewer laparotomies. Accordingly, the authors recommended against laparoscopic adhesiolysis in patients with two or more previous laparotomies. The high conversion rate in this study notwithstanding, the laparoscopic group as a whole (including conversions) experienced an overall reduction in postoperative complications.

Another potential advantage of laparoscopic adhesiolysis is that it results in fewer intra-abdominal adhesions than open laparotomy and thus may reduce the risk of recurrent bowel obstruction. However, a 1998 study found that despite a reduction in median length of stay, patients treated laparoscopically were at increased risk for early unplanned reoperation as a consequence of either incomplete relief of obstruction or complications.4 In fact, bowel perforation in the course of laparoscopic adhesiolysis often is not detected during the procedure and presents in a delayed fashion. Many such injuries are attributable either to insertion of the initial trocar or to delayed perforation of a thermal injury. When laparoscopic adhesiolysis fails to identify and relieve an obvious point of obstruction or when adhesiolysis is inadequate or unsafe, conversion to an open approach is indicated.

1. Wullstein C, Gross E: Laparoscopic compared with conventional treatment of acute adhesive small bowel obstruction. Br J Surg 90:1147, 2003 [PMID 12945085]

2. Fischer CP, Doherty D: Laparoscopic approach to small bowel obstruction. Semin Laparosc Surg 9:40, 2002 [PMID 11979409]

3. Vrijland WW, Jeekel J, Geldorp HJ, et al: Abdominal adhesions: intestinal obstruction, pain, and infertility. Surg Endosc 117:1017, 2003 [PMID 12632122]

4. Bailey IS, Rhodes M, O'Rourke N, et al: Laparoscopic management of acute small bowel obstruction. Br J Surg 85:84, 1998 [PMID 9462391]

Intestinal Obstruction

Question 1

A 70-year-old woman undergoing treatment for stroke develops complete colonic obstruction attributable to fecal impaction.

Which of the following modalities of management would be the most effective?
Please choose the single most appropriate answer to the question
  1. Disimpaction of feces under spinal/general anesthesia

    This is correct.

    Key Concept/Objective: To learn about the recommended management of colonic obstruction attributable to fecal impaction in a geriatric patient

    Fecal impaction in the rectum can sometimes present as complete colonic obstruction. Although disimpaction may be done at the bedside, it is extremely uncomfortable for the patient. The most expeditious and successful method of relieving the obstruction is to disimpact under general or spinal anesthesia. The PIEE procedure, which can also be performed at the bedside, has been found to successfully resolve fecal impaction. However, in various studies, it has been shown to be effective only 75% of the time in geriatric patients. Administration of polyethylene glycol is also effective but is more commonly used in pediatric patients.





  2. Pulsed-irrigated enhanced-evacuation (PIEE) procedure

    Sorry, this is incorrect. Try again!

  3. Using polyethylene glycol

    Sorry, this is incorrect. Try again!

  4. Any of the above

    Sorry, this is incorrect. Try again!



Question 2

A 50-year-old woman with partial bowel obstruction is being managed nonoperatively.

What would be the most sensitive clinical method to detect progressive obstruction?
Please choose the single most appropriate answer to the question
  1. Repeated abdominal examination every 8 hours

    Sorry, this is incorrect. Try again!

  2. Repeated abdominal examination by the same clinician every 6 hours

    Sorry, this is incorrect. Try again!

  3. Repeated abdominal examination every 12 hours

    Sorry, this is incorrect. Try again!

  4. Repeated abdominal examination by the same clinician every 3 hours

    This is correct.

    Key Concept/Objective: To learn about the clinical assessment of a patient of partial obstruction undergoing expectant treatment

    There is a definite risk of a patient with partial obstruction progressing to complete obstruction or strangulation and perforation while he is being observed. It is therefore crucial to be alert to changes in the patient's condition. Repeated examination of the abdomen by the same clinician is the most sensitive way of detecting progressive obstruction. Examinations should be performed no less frequently than every 3 hours. If abdominal pain, tenderness, or distention increases or the gastric aspirate changes from nonfeculent to feculent, abdominal exploration is usually indicated.







Question 3

A 65-year-old gentleman who had undergone surgery for ruptured abdominal aortic aneurysm 5 years ago is being managed for adhesive partial small bowel obstruction.

Regarding the likely success of nonoperative treatment in this patient, which of the following statements is true?
Please choose the single most appropriate answer to the question
  1. The nature of the previous operation does not influence the probability of success of medical treatment

    Sorry, this is incorrect. Try again!

  2. There is a higher likelihood of response to medical treatment if the previous operation was performed through midline laparotomy

    Sorry, this is incorrect. Try again!

  3. There is a lower likelihood of response to medical treatment if the previous operation was performed through midline laparotomy

    This is correct.

    Key Concept/Objective: To learn about the predictors of success of nonoperative treatment in adhesive bowel obstruction

    There are studies to suggest that the nature of the previous abdominal operation or the type of adhesions present may influence the probability that the obstruction will not respond to medical therapy. Operations associated with a lower likelihood of response to medical therapy include those performed through a midline incision; those involving the aorta, colon, rectum, appendix, or pelvic adnexa; and those done to relieve previous carcinomatous obstruction. Matted adhesions, which are more common in patients who have undergone midline incisions or colorectal procedures, are less amenable to conservative management than a simple obstructive band is. In the context of this kind of operative history, strong consideration should be given to surgical intervention if the obstruction does not resolve within 24 hours#x2014unless comorbid medical conditions tip the risk-benefit balance in the direction of nonoperative therapy.





  4. None of the above

    Sorry, this is incorrect. Try again!



Question 4

A 55-year-old woman who is American Society of Anesthesiologists (ASA) II is being worked up for surgery following failure of nonoperative treatment for adhesive small bowel obstruction.

Which of the following statements regarding the various treatment modalities is true?
Please choose the single most appropriate answer to the question
  1. Open adhesiolysis is recommended in patients with more than two previous laparotomies

    Sorry, this is incorrect. Try again!

  2. Laparoscopic adhesiolysis is superior to the open method in terms of postoperative outcome

    Sorry, this is incorrect. Try again!

  3. The probability of bowel injury is higher with laparoscopic adhesiolysis

    Sorry, this is incorrect. Try again!

  4. All of the above

    This is correct.

    Key Concept/Objective: To learn about the advantages of laparoscopic technique over the open technique of adhesiolysis

    Several clinical reports have demonstrated that laparoscopic adhesiolysis for acute small bowel obstruction is both feasible and safe. Laparoscopic or laparoscopic-assisted lysis of adhesions relieves bowel obstruction in more than 50% of patients and is associated with lower morbidity, earlier return of bowel function, quicker resumption of normal diet, and a shorter hospital stay than open operative lysis. At present, however, there are no prospective, randomized, controlled clinical trials comparing laparoscopic with open adhesiolysis. Patients with two or more previous laparotomies have been found to have a higher incidence of intraoperative complications than those with fewer laparotomies. It is therefore recommended to avoid laparoscopic adhesiolysis in patients with two or more previous laparotomies. The incidence of bowel injury has been observed to be higher with laparoscopic techniques in some retrospective studies. Laparoscopic adhesiolysis as a whole (including conversions) is associated with an overall reduction in postoperative complications.







Question 5

A 35-year-old woman has presented to the emergency room with acute intestinal obstruction.

What would be the most sensitive imaging modality to find the site and the cause of the obstruction?
Please choose the single most appropriate answer to the question
  1. Abdominal radiography

    Sorry, this is incorrect. Try again!

  2. Ultrasonography

    Sorry, this is incorrect. Try again!

  3. Contrast-enhanced helical computed tomography (CT)

    Sorry, this is incorrect. Try again!

  4. Fast magnetic resonance imaging (MRI)

    This is correct.

    Key Concept/Objective: To learn about the most sensitive imaging methods for establishing the location and cause of bowel obstruction

    Abdominal radiographs can be entirely normal in patients with complete, closed-loop, or strangulation obstruction. Therefore, if the patient's clinical profile and the results of physical examination are consistent with intestinal obstruction despite normal abdominal radiographs, abdominal ultrasonography, CT, or fast MRI should be performed immediately. Ultrasonography, CT, and fast MRI are all capable of detecting the cause of the obstruction, as well as the presence of closed-loop or strangulation obstruction. Prospective studies have demonstrated that the accuracy of CT in diagnosing bowel obstruction is higher than 95% and that its sensitivity and specificity are each higher than 94%. There is evidence to indicate that fast MRI with T2-weighted images is more sensitive, specific, and accurate than contrast-enhanced helical CT in establishing the location and cause of bowel obstruction. The advantages of fast MRI over helical CT are (1) that the image acquisition time is short (1 to 2 seconds per slice), which means that the image can be acquired in the space of a single held breath, (2) no contrast agents are required, and (3) the avoidance of ionizing radiation. In addition, because of its multiplanar capability, MRI is also more effective at demonstrating the transition point of the obstruction and the ability to provide real-time and functional evaluation.





Người đăng: vào lúc
Nhãn:

Không có nhận xét nào:

Đăng nhận xét

Đăng ký: Đăng Nhận xét (Atom)