The radiology of ileosigmoid knot.

The findings on the radiographs of 14 cases of ileosigmoid knot are presented and analysed. The clinical features and pathology of the condition are briefly described. The key radiological features consist of a dilated loop of pelvic colon, evidence of small intestinal obstruction and retention of faeces in an undistended proximal colon. The dilated loop usually lies in the right side of the abdomen and the limbs taper inferiorly into the right lower quadrant. Medial deviation of the distal descending colon is an inconsistant but highly specific finding. The radiographs readily permit distinction from primary volvulus of the small intestine and from non-obstructive surgical emergencies such as perforated viscus and ruptured ectopic pregnancy. The combination of radiographic findings may however be simulated by volvulus of the right colon, closed loop small intestinal obstruction and by volvulus of the pelvic colon complicated by peritonitis. The differential diagnosis is discussed and the value of sigmoidoscopy, rather than barium enema, emphasised.