A 77-year-old man presented after 3 days of diffuse abdominal pain, anorexia, and nausea. Four years before admission, he underwent an abdominoperineal resection for rectal cancer and was since admitted twice with episodes of partial small-bowel obstruction that resolved with conservative measures. Recently, he had developed and was treated for a urinary tract infection. In addition to his abdominal pain, he had profuse, watery stomal output. Although he wasafebrile, his white blood cell count was 50.7 ×103/µL. His abdomen was diffusely tender to deep palpation, but he exhibited no guarding or peritoneal signs. A computed tomographic scan of the abdomen showed a diffusely edematous bowel with ascites (Figure 1) and portal venous air (Figure 2).