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Intestinal obstruction is the inability of the intestinal tract to allow for regular passage of food and bowel contents secondary to mechanical obstruction or adynamic ileus. Adynamic ileus (paralytic ileus) is more common but is usually self-limiting and does not require surgical intervention. Mechanical obstruction can be caused by either intrinsic or extrinsic factors and generally requires definitive intervention in a relatively short period of time to determine the cause and minimize subsequent morbidity and mortality (Tables 86-1 and 86-2).

Table 86-1 Common Causes of Intestinal Obstruction
Table 86-2 Key Features of Ileus and Mechanical Bowel Obstruction

Both large and small intestines may be obstructed by various pathologic processes (Table 86-1). Extrinsic, intrinsic, or intraluminal processes precipitate mechanical obstruction. Differentiating small bowel obstruction (SBO) from large bowel obstruction (LBO) is important, because the incidence, clinical presentation, evaluation, and treatment vary depending on the anatomic site of obstruction. The small intestine is characterized by transverse linear densities that extend completely across the bowel lumen (plicae circulares). The colon is situated peripherally in the abdomen, is larger in diameter, and contains short, blunt, and thick projections (haustra) that arise from the bowel wall and extend only partially into the lumen. Haustra are less numerous and situated farther apart than plicae circulares.

The most common cause of SBO is adhesions after abdominal surgery. Although in most cases several months to years have passed from the time of the previous surgery, SBO may occur within the first few weeks after surgery. The second most common cause of SBO is incarceration of a groin hernia (see Chapter 87, Hernias in Adults). Other sites that occasionally are responsible for SBO secondary to hernia include the umbilicus, femoral canal, and, rarely, the obturator foramen. Umbilical hernias are more readily apparent and occur in any age group. Obturator or femoral hernias are much less common. Elderly females are particularly susceptible to these hernias, which may present with femoral or medial thigh pain. Finally, a defect in the mesentery itself may cause intestinal obstruction. Marathon runners have been noted to have bowel obstruction secondary to mesenteric defects.1

Bariatric surgery may be complicated by internal hernias after Roux-en-Y gastric bypass.2,3...

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