A newborn develops abdominal distension and bilious vomiting within the first 24 hours of life. A X-ray shows double bubble sign. What is the most likely diagnosis? A) Necrotizing enterocolitis B) Hirschsprung disease C) Duodenal atresia D) Intestinal malrotation E) Meconium ileus Correct Answer: C) Duodenal atresia Explanation: Duodenal atresia is a congenital condition where there is complete obstruction of the duodenum, often presenting with bilious vomiting and abdominal distension within the first 24 hours after birth. The double bubble sign on X-ray is characteristic, indicating gastric distension and a distended duodenum. Necrotizing enterocolitis (A) typically affects preterm infants and presents with abdominal distension, bloody stools, and signs of sepsis, but the X-ray findings are different. Hirschsprung disease (B) causes abdominal distension and constipation due to an absence of ganglion cells in the colon, but it does not present with bilious vomiting or the double bubble sign. Intestinal malrotation (D) presents with bilious vomiting and abdominal distension, but it typically presents later and may require an upper gastrointestinal contrast study to diagnose. Meconium ileus (E) is common in cystic fibrosis and causes abdominal distension and failure to pass meconium, but it is associated with ground-glass appearance on X-ray. Key Tips for PLAB 1: ✅ Abdominal distension, bilious vomiting, double bubble sign = Duodenal atresia ✅ Management = Surgical repair of the atresia
