Adhesions from previous abdominal operations are the most common cause of mechanical small bowel obstruction in adults. In the past, attempts to limit the number and magnitude of postoperative adhesions through instillation of agents such as heparin and hydroxyethyl starch into the peritoneal cavity proved unsuccessful. In recent years, a number of newer compounds such as oxidized, regenerated cellulose or the combination of sodium hyaluronate/carboxymethyl cellulose were approved by the FDA and are now in widespread use.

Patients with adhesive small bowel obstruction present with either partial or complete obstruction. In patients who are still passing flatus and have only moderate cramping, minimal abdominal distention, and display no signs of peritonitis, a trial period of nasogastric tube suction, hydration, and observation is worthwhile. Laparotomy has been avoided in 40% of such patients with nasogastric tube decompression and in 70% to 90% with endoscopic placement of long intestinal tubes. Patients with a history of complete bowel obstruction or with closed loop obstruction (steady pain), elevated temperature, signs of peritonitis on examination, progressive leukocytosis, or a “stepladder” appearance of dilated intestinal loops on flat plate radiographs of the abdomen should undergo urgent operation. Ischemia and even gangrene of the obstructed bowel can occur in the absence of the classical symptoms and signs.

Dehydration and electrolyte abnormalities (hyponatremic hypokalemic metabolic alkalosis) are common in patients with repeated episodes of vomiting related to proximal obstruction of the small bowel.