A baby is born with the small intestine protruding through the umbilical ring covered by amnion but with the cord attached to the apex. This is an omphalocele. Which embryological event failed?
- A Failure of the midgut to return to the abdominal cavity after physiological umbilical herniation at week 10–12 ✓
- B Failure of lateral folding of the embryonic disc at week 4
- C Failure of neural tube closure at the anterior neuropore
- D Failure of the dorsal mesentery to fuse with the posterior abdominal wall
Correct answer: A. Failure of the midgut to return to the abdominal cavity after physiological umbilical herniation at week 10–12
Explanation
Omphalocele (exomphalos) results from failure of the physiological midgut herniation — the midgut normally herniates into the umbilical cord at week 6, undergoes 270-degree counterclockwise rotation, and returns to the abdominal cavity by week 10–12. Failure of re-entry results in an omphalocele, covered by a translucent sac (amnion-peritoneum) with the umbilical cord inserting at its apex. Gastroschisis (bowel herniates through a paraumbilical abdominal wall defect, not covered by a sac) results from a vascular accident (disruption of omphalomesenteric vessels).
Reference: BD Chaurasia's Human Anatomy, 8th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.