A 2-day-old neonate presents with bilious vomiting and abdominal distension. Imaging shows a 'double bubble' sign. The embryological defect is failure of recanalization of the duodenum due to absence of which process?

• A Failure of the urorectal septum to descend
• B Failure of midgut rotation and fixation
• C Persistence of the vitelline duct
• D Failure of solid phase recanalization of the duodenal lumen (6th–8th week) ✓

Explanation

During the 5th–8th week of development, the duodenal lumen becomes temporarily occluded by rapid proliferation of endodermal cells (solid stage). Recanalization normally restores the lumen. Failure of recanalization produces duodenal atresia, presenting with bilious vomiting (bile duct enters duodenum proximal to the obstruction) and the 'double bubble' sign on X-ray (dilated stomach and first part of duodenum). Duodenal atresia is associated with Down syndrome. Midgut volvulus can also obstruct the duodenum but by a different mechanism.

Reference: BD Chaurasia's Human Anatomy, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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