Air under the diaphragm in patients undergoing continuous ambulatory peritoneal dialysis (CAPD)

To understand the significance of pneumoperitoneum in patients undergoing continuous ambulatory peritoneal dialysis (CAPD), we reviewed 110 upright x-rays of 33 patients. Only 3 x-rays belonging to 2 patients displayed large amounts of air under the diaphragm. One patient had documented colonic perforation and the other patient used a faulty technique that introduced air into the abdomen. Five additional asymptomatic patients showed minute amounts of air. We conclude that large amounts of air, as defined radiographically by an air shadow of more than 5 mm in height, is unusual in CAPD patients and should be taken seriously as suggestive of bowel perforation until proven otherwise.