A 6-week-old infant born in Delhi presents with intermittent bilious vomiting and failure to thrive. Abdominal examination reveals visible peristaltic waves from left to right. Ultrasound shows the superior mesenteric artery (SMA) positioned to the left of the superior mesenteric vein (SMV). The child is afebrile and haemodynamically stable. What is the most appropriate next step in management?

Explanation

## Clinical Context This infant has imaging findings suggestive of malrotation (SMA to the left of SMV is abnormal; normally SMA is to the right). However, the clinical presentation is subacute with intermittent symptoms and haemodynamic stability — not acute volvulus. The next step is to confirm the diagnosis and assess for associated complications (volvulus, obstruction). ## Diagnostic Approach ```mermaid flowchart TD A[Suspected malrotation on ultrasound]:::outcome --> B{Acute volvulus signs?}:::decision B -->|Yes: acute distension, peritonitis| C[Immediate OR]:::urgent B -->|No: subacute symptoms| D[Upper GI contrast study]:::action D --> E{Ligament of Treitz position?}:::decision E -->|Normal position| F[Observe, reassess]:::outcome E -->|Abnormal/volvulus| G[Surgical consultation]:::action G --> H[Ladd's procedure]:::action ``` ## Key Point: **Upper GI contrast study is the gold standard for diagnosing malrotation.** It shows: - Position of the ligament of Treitz (normally at the left of the midline at the level of the duodenojejunal junction). - Abnormal 'corkscrew' or 'whirlpool' appearance if volvulus is present. - Duodenal obstruction patterns. ## High-Yield: - **SMA-SMV relationship on ultrasound** is a screening tool but NOT diagnostic on its own. Reversed SMA-SMV position (SMA left of SMV) is highly suggestive of malrotation but requires confirmation with contrast study. - **Ligament of Treitz position** is the key anatomical landmark: normally it lies at the left of the midline at the level of the duodenojejunal flexure. - Intermittent symptoms suggest incomplete or intermittent volvulus — surgery can be planned electively after diagnosis confirmation. ## Clinical Pearl: Visible peristaltic waves from left to right (reverse of normal right to left) suggest abnormal intestinal rotation. Combined with SMA-SMV reversal, this strongly indicates malrotation, but contrast confirmation prevents unnecessary surgery if anatomy is actually normal. ## Mnemonic: **TREITZ** = Ligament of Treitz marks the duodenojejunal flexure and is the key landmark for assessing rotation. Its position (left of midline) is diagnostic.