A 3-day-old neonate presents with bilious vomiting and abdominal distension. An upper gastrointestinal contrast study shows the duodenojejunal junction lying to the right of the spine and a spiral ('corkscrew') course of the duodenum. Normal embryonic midgut rotation consists of:

• A 270 degrees anticlockwise rotation around the superior mesenteric artery ✓
• B 90 degrees clockwise rotation around the coeliac axis
• C 180 degrees anticlockwise rotation around the inferior mesenteric artery
• D 360 degrees clockwise rotation around the portal vein

Explanation

The midgut loop herniates into the umbilical cord and rotates 270 degrees anticlockwise (counterclockwise when viewed from front) around the axis of the superior mesenteric artery before returning to the abdomen. Incomplete or reversed rotation leaves the duodenojejunal junction misplaced and shortens the small bowel mesentery, predisposing to midgut volvulus, seen here as the corkscrew sign. Rotation occurs around the SMA, never around the coeliac, inferior mesenteric, or portal vessels.

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

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Written and medically reviewed by the StethoPrep medical team.