What gastrointestinal condition is indicated by a double bubble sign on an X-ray in neonates?

The identification of a double bubble sign on an X-ray in neonates strongly indicates duodenal atresia. This sign typically appears when there is an obstruction in the duodenum, which leads to the accumulation of air in the stomach and proximal duodenum, resulting in the characteristic "double bubble" appearance. The first bubble represents the distended stomach while the second bubble represents the distended proximal duodenum. This condition is often associated with Down syndrome and can present shortly after birth with symptoms such as bilious vomiting.

In contrast, Hirschsprung's disease primarily involves an absence of ganglion cells in a segment of the bowel, leading to functional obstruction but not typically presenting with a double bubble sign. Intussusception is more common in older infants and children, presenting with different imaging characteristics that include multiple air-fluid levels and a "target sign" rather than the classic double bubble. Appendicitis usually presents in a much older demographic and does not feature the double bubble sign as its hallmark finding. Thus, the presence of a double bubble sign specifically aligns with the diagnosis of duodenal atresia in neonates.