A neonate has bilious vomiting and upper abdominal distension. Upper GI contrast study shows the duodenum completely encircled by a ring of pancreatic tissue. This anomaly results from which developmental event?

• A Failure of fusion of the dorsal and ventral pancreatic buds
• B Abnormal migration of spleen primordium into the pancreatic tail
• C Excessive apoptosis of the ventral pancreatic bud
• D Bifid ventral pancreatic bud encircling the duodenum during rotation ✓

Explanation

Annular pancreas occurs when the ventral pancreatic bud divides into two lobes that migrate around opposite sides of the duodenum during its rotation, fusing posteriorly with the dorsal bud and encircling the second part of the duodenum. Failure of bud fusion instead causes pancreas divisum, where most drainage occurs through the minor papilla. Excessive apoptosis would cause pancreatic hypoplasia or agenesis. The condition presents with duodenal obstruction and may be associated with Down syndrome.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.