Differential Diagnosis for Abdominal Distention and Bilious Vomiting in a Newborn

The clinical presentation of abdominal distention and bilious vomiting in a newborn, especially when accompanied by lethargy and sunken fontanelles, suggests a congenital obstruction. The provided X-ray of the abdomen, although not described, is crucial for narrowing down the differential diagnoses. Based on the symptoms and the typical findings associated with such conditions, the following differential diagnoses can be considered:

• Single Most Likely Diagnosis

  • Duodenum: The presence of bilious vomiting is highly suggestive of an obstruction below the ampulla of Vater, where bile enters the intestine. Duodenal atresia or stenosis is a common cause of such symptoms and is consistent with the clinical presentation. The "double-bubble" sign on an abdominal X-ray, which shows two air-filled structures (the stomach and the duodenum) with no gas in the small bowel beyond, is characteristic of duodenal atresia.

• Other Likely Diagnoses

  • Ileum: Intestinal obstruction due to atresia or stenosis of the ileum could also present with bilious vomiting, although it might occur slightly later than with more proximal obstructions. The X-ray findings would typically show multiple air-filled loops of bowel.
  • Pylorus: While pyloric stenosis is a cause of vomiting in infants, it typically presents with non-bilious projectile vomiting, usually starting a few weeks after birth. However, it's less likely given the bilious nature of the vomiting in this case.

• Do Not Miss Diagnoses

  • Esophagus: Esophageal atresia with or without tracheoesophageal fistula is a critical diagnosis not to miss, as it can lead to severe respiratory complications. However, the primary symptom would be non-bilious vomiting or choking during feeding, rather than abdominal distention and bilious vomiting.
  • Common bile duct: Obstruction of the common bile duct, such as biliary atresia, would not typically present with acute abdominal distention and bilious vomiting immediately after birth but could lead to jaundice.

• Rare Diagnoses

  • Various other rare congenital anomalies, such as jejunal atresia, volvulus, or intestinal malrotation, could also present with similar symptoms. These conditions might have distinctive X-ray findings, such as a "whirlpool" sign in malrotation with volvulus, and require prompt surgical intervention to prevent intestinal necrosis.