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]

SAQ 2 — The time-critical volvulus (10 marks)

A previously well term infant, five days old, who was feeding normally and passed meconium on day one, suddenly vomits bright green fluid, becomes listless and refuses feeds. On examination the heart rate is 180, the capillary refill is 4 seconds, and the abdomen is tense and tender with a dusky discolouration of the abdominal wall. A plain abdominal radiograph shows a non-specific gas pattern with no double-bubble and no free air. [5]

a) What is the most likely diagnosis, and why does the plain radiograph not exclude it? (3 marks) [5]

The most likely diagnosis is malrotation with midgut volvulus. A previously well term infant with sudden bilious vomiting, shock and a tender discoloured abdomen has volvulus with ischaemia until proven otherwise. The plain radiograph is often normal or shows only non-specific gastric distension early in volvulus — a reassuring radiograph is the classic trap, because the bowel is obstructed but empty of gas. [5]

b) Describe the immediate management and the specific reason you would not wait for a contrast study in this infant. (4 marks) [5]

The immediate management is aggressive resuscitation (IV access, isotonic crystalloid boluses in 10 mL/kg aliquots, NG decompression, antibiotics) and an immediate surgical review for emergency laparotomy. The reason not to wait for a contrast study is that this infant is unstable and peritonitic, with clinical evidence of ischaemia — the contrast upper GI series is for the infant who is stable enough to wait. Waiting for imaging in a peritonitic infant with volvulus is how a salvageable midgut becomes a short gut. [5]

c) Describe the operation performed and the specific additional procedure included, with its rationale. (2 marks) [5]

The operation is the Ladd procedure: untwist the volvulus counter-clockwise, divide the Ladd bands, widen the mesenteric base by laying the bowel out in non-rotation, resect any non-viable bowel, and perform an appendicectomy. The appendicectomy is included because after the procedure the caecum lies on the left, so future appendicitis would present in an atypical location and be a diagnostic trap. [5]

d) What determines the long-term prognosis, and what is the worst-case trajectory? (1 mark) [5]

The prognosis is determined by the amount of bowel salvaged. The worst-case trajectory is short-bowel syndrome requiring lifelong parenteral nutrition, intestinal rehabilitation, and possibly small-bowel transplantation — the consequence every minute of delay risks. [5]