REVERSED rotation of the mid-gut with resultant retroposition of the transverse colon is probably the rarest of all developmental anomalies of the colon.1 This unusual condition results from an error in the second stage of rotation of the mid-gut. When the mid-gut returns to the abdominal cavity from the umbilical cord during the 10th week of embryonic life, a 90-degree clockwise rotation occurs (inverted rotation) rather than the normal 270-degree counterclockwise rotation. Hence, the transverse colon passes dorsal to the superior mesenteric artery at the angle of its emergence from the aorta, and the duodenum passes ventral to both.
An unusual case of reversed rotation complicated by partial obstruction of the transverse colon and partial duodenal obstruction will be described, and the 27 previously reported examples2 of reversed rotation will be discussed.
REPORT OF CASE
S. J. W., a white girl, weighed 8 lb. 10 oz. (3,910 gm.)