A unique late mechanical complication of jejunoileal bypass.

The consequences of jejunoileal bypass include not just metabolic derangements, though the frequency and severity of these problems have led to the procedure being abandoned in the treatment of morbid obesity, but a variety of mechanical complications as well. In this report, a new mechanical complication is presented: Intussusception of the defunctionalized ileum into the sigmoid colon, an intussusception caused by malignant lymphoma of the ileum. Because the patient had pain but no evidence of obstruction, the ileal tumor was fortuitously discovered during flexible sigmoidoscopy.