Bilious vomiting and neonatal intestinal obstruction — formative SAQs

SAQ 1 — The double-bubble and Down syndrome (10 marks)

A term male infant born after a pregnancy complicated by polyhydramnios vomits green-stained fluid at 18 hours of life. Antenatal scans showed a double-bubble. The infant has features consistent with Down syndrome. The abdomen is soft and non-distended. A plain abdominal radiograph shows two large gas-filled structures in the upper abdomen with no distal bowel gas. ^[4]

a) What is the diagnosis, and what is the key anatomical reason the vomit is bilious? (2 marks) ^[4]

The diagnosis is duodenal atresia in an infant with Down syndrome, antenatal polyhydramnios and a double-bubble. The vomit is bilious because the obstruction lies distal to the ampulla of Vater, where bile enters the duodenum, so bile cannot pass onward and is regurgitated. ^[4]

b) Outline your immediate management, in the correct order, before any imaging is obtained. (4 marks) ^[10]

The immediate management is resuscitation and decompression in a fixed order: keep the infant nil by mouth, pass a large-bore (10–12 French) nasogastric tube on free drainage to decompress the stomach and prevent aspiration, establish intravenous access and resuscitate with isotonic crystalloid (normal saline or Hartmann's) in 10 mL/kg boluses to restore perfusion, correct glucose and electrolytes, start broad-spectrum antibiotics, and make an urgent paediatric surgical referral. The imaging follows stabilisation, never precedes it. ^[10]

c) What definitive operation is performed, and what additional workup is required before surgery because of the associated syndrome? (2 marks) ^[4]

The definitive operation is a diamond-shaped duodenoduodenostomy (the Kimura procedure), bypassing the atresia. Because of the Down syndrome association, the infant requires a karyotype confirmation and an echocardiogram to exclude the cardiac anomalies (classically an endocardial cushion defect) that shape the anaesthetic and perioperative risk. ^[4]

d) What is the prognosis after elective repair, and what governs the long-term outcome? (2 marks) ^[4]

The prognosis after elective repair is excellent, with near-normal long-term gastrointestinal function. The outcome is governed chiefly by the cardiac and chromosomal associations rather than the bowel itself, in the absence of major cardiac disease. ^[4]