The double bubble sign is most characteristic of which condition?

• A. Duodenal atresia
• B. Meconium ileus
• C. Esophageal atresia
• D. Bowel atresia

Answer: (A)

The double bubble sign appears on a neonatal abdominal radiograph when gas is trapped in two adjacent, upper abdominal structures—the stomach and the proximal duodenum—with little or no gas beyond. This pattern indicates a high obstruction at the level of the duodenum, preventing passage of contents into the distal bowel.

This sign is most characteristic of duodenal atresia, a congenital blockage from failure of recanalization of the duodenum during development. It explains the two prominent bubbles and the lack of distal gas. Clinically, it often presents with bilious vomiting shortly after birth and may be associated with polyhydramnios and certain chromosomal conditions.

Meconium ileus would show gas in the distal bowel with a soap-bubble appearance more centrally in the abdomen, not two discrete proximal bubbles. Esophageal atresia can produce gas in the stomach if a fistula is present, but it does not create the classic two-bubble pattern of proximal duodenal obstruction. Bowel atresias elsewhere typically show multiple dilated loops and air-fluid levels throughout the abdomen rather than two focused upper-abdominal bubbles. So the two-bubble radiographic appearance points most specifically to duodenal atresia.