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Adhesiolysis – Open
Goals/Objectives
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Indications
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Anatomic considerations
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Technical considerations
Small Bowel Obstruction
From Fazio VW, Church JM, and Delaney CP: Current Therapy in Colon and Rectal Surgery, 2nd edition (Mosby 2004)
Small bowel obstruction is one of the most common conditions encountered by colorectal surgeons. A recent analysis of Health Care Financing Administration data found that 14% of patients undergoing abdominal surgery will require hospitalization for small bowel obstruction within 2 years and that 2.4% will require adhesiolysis; colorectal procedures, in particular, seem to carry the highest risk. Approximately 300,000 operations are performed each year in the United States for this disorder at a cost of over $1 billion.
Postoperative adhesions are the most common cause of small bowel obstruction, accounting for 50 to 75% of cases in recent series. Hernias and malignancy account for most of the remainder (20 to 40%), and volvulus, Crohn's disease, chronic radiation enteritis, intussusception, and gallstone ileus make up only a fraction.
Perhaps the most critical components in the management of patients with bowel obstruction are the recognition and prevention of significant bowel ischemia. Timely surgical intervention, prior to the development of transmural necrosis, will limit complications and improve outcome. In one recently published series of over 1000 patients undergoing surgery for small bowel obstruction, nonviable strangulated bowel was present at laparotomy in only 16% of cases but the risk of death in this group was increased fourfold.
Presentation and Diagnosis
Nausea and vomiting, crampy pain, abdominal bloating, and obstipation are the hallmark signs of small bowel obstruction. The degree to which each of these contributes to the clinical picture will depend on the location, degree, and duration of the obstruction. A thorough history and physical examination should be performed. The patient is questioned regarding previous surgical procedures, known hernias, prior abdominal or pelvic radiation therapy, history of malignancy, signs or symptoms of undiagnosed cancer, or personal or family history of Crohn's disease. Significant comorbidities should also be sought. A general assessment of the patient's toxicity is made and vital signs obtained. The presence or absence of distention, surgical scars, or ventral and groin hernias is noted, and the abdomen is palpated to assess for peritonitis, masses, or incarcerated hernias not obvious on inspection. Percussion may reveal tympany from gas-filled bowel loops, and on auscultation characteristic high-pitched, tinkling bowel sounds may be heard. A digital rectal examination should always be done in order to exclude an obstructing rectal cancer.
Laboratory tests include white blood cell count, hematocrit, electrolytes, serum bicarbonate, blood urea nitrogen, and creatinine. Amylase and lipase are usually requested to rule out pancreatitis with associated ileus. Serum lactate levels may be obtained, but they should not be relied upon as a sole indicator of ischemia.
Commonly accepted signs of strangulated bowel are fever, tachycardia, leukocytosis, sepsis, peritonism, and the presence of continuous as opposed to intermittent pain. If any of these signs are found, the suspicion of ischemia should be high; however, these signs may also be found in many patients without strangulation and are, therefore, nonspecific. In general, the diagnosis of strangulated bowel should be made based on a combination of clinical experience and the foregoing indicators. In many cases, however, this determination is not made until laparotomy. Timely surgical intervention, therefore, may be the best means of avoiding the progression to bowel ischemia. This fact is underscored by a report from Sarr and colleagues, who found that the traditional clinical parameters usually employed to predict strangulation were neither sensitive nor specific. Nearly one third of patients with strangulation were not diagnosed until the time of surgery.
Radiographic Studies
Plain Radiographs
An acute abdominal series is the initial imaging study performed in most patients suspected of having small bowel obstruction and consists of both upright and supine abdominal films and an upright chest x-ray. Typical findings include dilated, air-filled loops of small bowel; air-fluid levels; and an absence or paucity of colonic air. These findings may be absent, however, when the obstruction is proximal or the dilated bowel loops are mostly fluid-filled. The sensitivity of plain radiographs in detecting small bowel obstruction is approximately 60%. The finding of pneumatosis intestinalis or portal vein gas is worrisome for advanced bowel ischemia.
Computed Tomography
Abdominopelvic computed tomographic (CT) scanning is being used increasingly as a primary imaging modality in patients with small bowel obstruction. In addition to establishing the diagnosis, CT scan may also be able to precisely define a transition point and reveal secondary causes of obstruction such as tumors, hernias, intussuception, volvulus, or inflammatory conditions such as Crohn's disease and radiation enteritis. CT scan may also reveal closed loop obstruction or signs of progressive ischemia, such as bowel wall thickening, pneumatosis, or portal vein gas. Several studies have shown that the sensitivity of CT in diagnosing small bowel obstruction approaches 90 to 100%.
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