A neonate born at 35 weeks presents at 12 hours of age with bilious vomiting and abdominal distension. Plain X-ray shows a 'double bubble' sign with no distal gas. What is the most likely diagnosis and the associated chromosomal anomaly?
- A Malrotation with volvulus; no chromosomal association
- B Jejunal atresia; trisomy 18
- C Duodenal atresia; Down syndrome (trisomy 21) in 30% of cases ✓
- D Pyloric stenosis; Turner syndrome
Correct answer: C. Duodenal atresia; Down syndrome (trisomy 21) in 30% of cases
Explanation
The 'double bubble' sign on plain X-ray (distended stomach and proximal duodenum with absent distal gas) is pathognomonic of duodenal atresia, which results from failure of recanalisation of the duodenal lumen during weeks 8–10 of embryogenesis. Approximately 30% of cases are associated with Down syndrome (trisomy 21). Other associations include cardiac defects and annular pancreas. Malrotation with volvulus produces bilious vomiting but distal gas is present and requires emergency surgery. Jejunal atresia presents with multiple air-fluid levels.
Reference: Bailey & Love's Short Practice of Surgery, 27th ed.
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