CHAPTER 11 Small Bowel Resection
Case Study
Supine and upright abdominal radiographs show dilated loops of small bowel, air–fluid levels, and minimal air in the colon, consistent with a small bowel obstruction. A computed tomography (CT) scan of the abdomen and pelvis shows dilated loops of small bowel and a point of transition to collapsed bowel in the right lower quadrant (Fig. 11-1).
INDICATIONS FOR SMALL BOWEL RESECTION
I. Small Bowel Obstruction
A. Postoperative adhesions are the most common cause of small bowel obstruction. Other etiologies include hernias (e.g., inguinal and femoral), volvulus, intussusception, benign and malignant tumors, Crohn’s disease, gallstone ileus, foreign bodies, parasites, bezoars, and radiation enteritis. Bowel obstructions are classified as complete or partial. This distinction is often inferred from the severity of clinical symptoms and radiographic findings (e.g., absence of colonic air on abdominal radiograph). Patients with a bowel obstruction typically present with nausea and vomiting, diffuse abdominal pain, abdominal distention, and obstipation. Dehydration may result from vomiting and GI fluid secretion into obstructed bowel. A potential endpoint of many obstructive processes is bowel ischemia. This may result from compromise of the vascular supply to the small bowel in an incarcerated hernia (strangulation) or from progressive distention of obstructed bowel, leading to increased wall pressure, obstruction of venous outflow, and subsequent arterial compromise.
B. The initial management of a small bowel obstruction includes nasogastric tube (NGT) decompression and fluid resuscitation. Small bowel obstructions resulting from adhesions are more likely to resolve without surgical management than are obstructions from other causes. Focal or worsening abdominal tenderness, signs of peritonitis, fever, hemodynamic instability, leukocytosis, and lactic acidosis, suggesting bowel compromise, require urgent operative exploration. In addition, patients with complete obstructions and those without a history of abdominal surgery are more likely to require early operative intervention. Operative management is primarily aimed at relieving the obstruction, which may require lysis of adhesions, hernia repair, or bowel resection.
II. Perforation may result from bowel necrosis as a result of a number of processes, including small bowel obstruction and acute mesenteric ischemia. Alternatively, perforation may occur without preceding necrosis of the small bowel wall (e.g., perforated small bowel tumors, perforated duodenal ulcers, and Crohn’s disease). Patients typically present with fever, hemodynamic instability, and focal or generalized peritonitis. With few exceptions, bowel perforations mandate immediate surgical exploration and resection of perforated segments.
III. Bleeding from the small bowel may be caused by small bowel tumors or by Meckel’s diverticulum. In the latter case, bleeding is usually caused by exposure of the surrounding small bowel mucosa to secretions from ectopic gastric mucosa within the diverticulum. Small bowel arteriovenous malformations and hemangiomas are two additional sources of small bowel bleeding.
IV. A fistula is defined as an abnormal connection between two epithelialized surfaces. Some examples of small bowel fistulas include enterocutaneous fistulas (fistula between bowel and skin) and fistulas between the small bowel and the urinary tract or vagina. Small bowel fistulas may result from iatrogenic bowel injuries during surgery or an anastomotic leak after bowel resection. Additionally, cancer, Crohn’s disease, infection, and radiation may all lead to fistula formation. Initial treatment of a small bowel fistula usually consists of bowel rest and total parenteral nutrition (TPN) to decrease fistula output and optimize nutrition. In some patients, this treatment leads to closure of the fistula tract. However, in patients in whom conservative management is unsuccessful, surgery is performed to excise the fistula tract and resect involved segments of bowel.
