A 2-day-old female neonate has bilious vomiting from birth, abdominal distension, and failure to pass meconium. X-ray shows a 'double bubble' sign. At surgery, a duodenal atresia is found at the level of the second part of the duodenum. The embryological basis of this defect is:

• A Volvulus of the midgut at 8 weeks gestation
• B Failure of rotation of the midgut loop
• C Failed recanalization of the duodenal lumen after the solid cord stage (5th–10th week) ✓
• D Annular pancreas compressing the duodenum externally

Explanation

Duodenal atresia results from failure of recanalization of the duodenal lumen that normally undergoes a transient solid epithelial cord phase between 6–10 weeks of gestation, followed by vacuolization and recanalization. Incomplete or failed recanalization produces atresia (most common), stenosis, or a web/membrane. The double bubble sign on X-ray represents air in the stomach and proximal duodenum with no distal gas. Annular pancreas encircles the duodenum externally and is a separate (and occasionally co-existing) lesion; it causes obstruction but is not intrinsic atresia. Surgical repair is diamond-shaped duodeno-duodenostomy (Kimura procedure).

Reference: Bailey & Love's Short Practice of Surgery, 27th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.