A 3-day-old neonate presents with bilious vomiting. Abdominal X-ray shows a 'double bubble' sign with no distal gas. The most important preoperative investigation before surgical correction is:

• A Echocardiography — 30-40% of duodenal atresia patients have associated cardiac defects ✓
• B Upper GI contrast study to confirm duodenal atresia
• C Chromosomal karyotyping — immediate genetic diagnosis required pre-op
• D Abdominal ultrasound to assess pancreatic anatomy

Explanation

The 'double bubble' sign with no distal gas on X-ray is diagnostic of complete duodenal atresia. The key preoperative investigation is echocardiography, as approximately 30-40% of duodenal atresia cases have associated congenital cardiac defects (most commonly VSD), and 25-30% have Down syndrome (trisomy 21). Cardiac anomalies must be identified before surgical correction (Kimura's diamond-shaped duodeno-duodenostomy) as they directly affect anaesthetic risk and perioperative management. Upper GI contrast is not needed when double bubble with absent distal gas is present (diagnosis is complete). Karyotyping is important but can be done post-stabilization. Ultrasound for pancreas is secondary.

Reference: Bailey & Love's Short Practice of Surgery, 27th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.