A 3-day-old neonate presents with bilious vomiting. Surgery reveals the caecum lying in the right upper quadrant with fibrous bands crossing the duodenum. The primary embryological error is:

• A Failure of recanalization of the duodenum
• B Failure of descent of the caecal bud into the iliac fossa alone
• C Reversal of the cranio-caudal axis of the foregut
• D Incomplete rotation and fixation of the midgut loop after its return to the abdomen ✓

Explanation

Normal midgut rotation involves 270 degrees counterclockwise turning about the superior mesenteric artery before the loop returns to the abdomen. Incomplete rotation leaves the caecum high and unfixed, and abnormal peritoneal bands called Ladd bands cross the duodenum, causing extrinsic obstruction and predisposing to midgut volvulus. Recanalization failure produces intrinsic duodenal atresia with a double bubble sign, not mobile caecum with bands.

Reference: Langman's Medical Embryology, 14th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.