A wide variety of pathologies can affect the small bowel and require surgical resection. Interestingly, despite being the longest segment of the GI tract, primary malignant tumors of the small bowel occur less frequently than other sites. The most common tumor of the small intestines is small bowel adenocarcinoma; other possible neoplasms include carcinoid tumor (Fig. 11.1), gastrointestinal stromal tumor (GIST), and lymphoma (Fig. 11.2). Metastatic lesions can also involve the small bowel, most commonly from melanoma or carcinomatosis deposits from other GI tumors.

Intussusception describes the condition where a portion of the small bowel prolapses over itself, similar to the way the segments of a collapsible telescope slide over one another. Intussusception causes intense crampy abdominal pain as the small bowel peristalses against the point of obstruction. The lead point of this process typically has some abnormality that initiates the telescoping. In children, that lead point is usually a Peyer’s patch—an area of benign lymphoid nodules within the bowel wall. In adults, the lead point is almost always a malignant tumor. As a result, while intussusception in children can be managed non-operatively, in adults it is necessary to resect the bowel with its inciting pathology.

Crohn’s disease is a type of inflammatory bowel disease of unknown etiology. Symptoms include chronic abdominal pain, diarrhea, and weight loss. These symptoms can be accompanied by various extra-intestinal manifestations including ankylosing spondylitis, erythema nodosum, primary sclerosing cholangitis, and uveitis. Crohn’s disease can involve any portion of the GI tract, causing aphthous ulcers in the mouth to perianal fistulae, but strictures of the terminal ileum are the most classic presentation. Multiple strictures may be present with skipped areas of normal appearing bowel in between. In the past, aggressive resection of all effected bowel led to many patients developing short gut syndrome. It is now recognized that resection does not prevent recurrence of Crohn’s, and therefore stricturoplasty is the preferred approach, allowing both relief of the stricture and preservation of bowel length. Bowel resection for Crohn’s disease should be reserved for areas of severe obstruction, perforation, or fistula formation. Ultimately, Crohn’s disease is a systemic illness and surgery can be used to manage complications, but does nothing to cure the underlying disease.

A Meckel’s diverticulum is a congenital outpouching of the GI tract that occurs when the vitelline duct fails to regress completely. The “Rule of Two’s” describes several classic features of a Meckel’s diverticulum: it occurs in 2 % of the population, only 2 % of affected individuals will develop symptoms, presentation typically occurs before age 2, the diverticulum is usually located within 2 ft of the terminal ileum and is 2 in. long, and finally—two types of ectopic tissues (gastric or pancreatic) can be found within a Meckel’s diverticulum. The potential complications of a Meckel’s diverticulum include intussusception, diverticulitis, or GI bleeding. These events are treated with resection of the portion of small bowel containing the diverticulum.

An arteriovenous malformation (AVM) is a focal vascular anomaly of the small intestine where there is an abnormal communication between local arteries and veins. These tiny lesions can cause spontaneous, intermittent, and massive GI bleeding. Often AVM bleeds are self-limited, however if there is continued hemorrhage, an emergent resection of the effected bowel may be indicated. Precise localization of the point of bleeding can be notoriously difficult. Intraoperative inspection of the small bowel is not useful, since the intestine becomes diffusely full of blood, and these lesions are not visible from the serosal aspect of the bowel. Capsule endoscopy, angiography, and intraoperative endoscopy can be utilized to help identify the point of bleeding.