A neonate presents with bilious vomiting and abdominal X-ray shows partial duodenal obstruction with gas in the distal bowel. At surgery, pancreatic tissue is seen completely encircling the second part of the duodenum. This resulted from:

• A Failure of recanalisation of the duodenal lumen
• B Abnormal migration of splenic primordium into the pancreatic head
• C Failure of fusion of the dorsal and ventral pancreatic ducts
• D Bifid ventral pancreatic bud encircling the duodenum during rotation ✓

Explanation

Annular pancreas occurs when the ventral pancreatic bud is bifid; the two portions migrate in opposite directions around the duodenum during its rotation and fuse, forming a ring of pancreatic tissue that compresses the second part of the duodenum. Failure of recanalisation causes complete duodenal atresia with a double bubble sign and no distal gas, whereas annular pancreas typically causes partial obstruction with distal gas present.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.