## Clinical Approach to Neonatal Bilious Vomiting **Key Point:** Bilious vomiting in a neonate is intestinal obstruction until proven otherwise. The 'double bubble' sign suggests duodenal obstruction, but malrotation with volvulus must be excluded before proceeding to surgery. ### Why Contrast Study First? **High-Yield:** Upper GI contrast study (or abdominal ultrasound in experienced centres) is the gold standard to identify the position of the ligament of Treitz and rule out malrotation. This is a life-saving investigation because: 1. **Malrotation with volvulus** is a surgical emergency requiring immediate Ladd's procedure 2. **Duodenal atresia** (intrinsic obstruction) requires duodenoduodenostomy 3. The two conditions require **different surgical approaches** — operating without confirming anatomy risks catastrophic outcome ### Management Sequence ```mermaid flowchart TD A[Neonate: Bilious vomiting + Double bubble]:::outcome --> B[NPO, NG tube, IV fluids]:::action B --> C[Urgent upper GI contrast study]:::action C --> D{Ligament of Treitz position?}:::decision D -->|Normal position| E[Duodenal atresia: Duodenoduodenostomy]:::action D -->|Abnormal/Malrotation| F[Malrotation ± volvulus: Ladd's procedure]:::urgent D -->|Volvulus present| G[Emergent Ladd's procedure]:::urgent ``` **Clinical Pearl:** The 'double bubble' alone does NOT differentiate duodenal atresia from malrotation with volvulus. Contrast study identifies the position of the duodenojejunal flexion (ligament of Treitz) — normally at the left of the midline at the level of L2. **Tip:** In resource-limited settings, abdominal ultrasound can assess for volvulus (whirlpool sign) and malrotation (reversed superior mesenteric artery–vein relationship), but upper GI contrast remains the reference standard. [cite:Sabiston Textbook of Surgery Ch 67] 
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