A neonate presents with bilious vomiting within the first 48 hours of life. Upper GI contrast study shows the duodenojejunal flexure to the right of the midline and a corkscrew appearance of the proximal jejunum. The normal developmental event whose failure caused this condition involves rotation of the midgut loop through:
- A 90 degrees anticlockwise
- B 180 degrees clockwise
- C 270 degrees anticlockwise about the axis of the superior mesenteric artery ✓
- D 360 degrees clockwise about the axis of the coeliac trunk
Correct answer: C. 270 degrees anticlockwise about the axis of the superior mesenteric artery
Explanation
The midgut loop herniates into the umbilical cord and rotates 270 degrees anticlockwise around the axis of the superior mesenteric artery before returning to the abdomen. Incomplete or reversed rotation leaves the duodenojejunal flexure to the right and the caecum high and mobile, allowing Ladd bands and midgut volvulus, which explains the bilious vomiting and corkscrew sign. Rotation is anticlockwise, never clockwise.
Reference: Moore and Persaud, The Developing Human, 11th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.