Patient 1: A 79-year-old man was admitted to the University Hospitals with a two-month history of upper abdominal pain and nausea. On the day of admission he underwent uneventful proctosigmoidoscopy to a level of 17 cm. On the next day, following administration of a preparation consisting of cathartics and enemas, ba r ium-enema examinat ion was a t tempted. T h e radiologist performing the examination reported that "barium did not flow into the sigmoid and dissected outside the lumen of the alimentary tract" (Figs. 1 and 2). Barium was seen outside the lumen of the rectum extending into the presacral space without extension into the peritoneal cavity. Administration of antibiotics was started and the patient was prepared for operation. General anesthesia was used. Sigmoidoscopy revealed a perforation anteriorly, approximately 5 cm from the anal verge. The perforation was 1.5-2 cm in diameter and was surrounded by an inflammatory reaction. A lower midline incision was made in order to explore the abdomen. A large amount of barium was visible through the retroperitoneum in the pelvis. Exploration of the rest of the abdominal viscera revealed an advanced gastric malignancy,