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Duodenal atresia is a congenital malformation characterized by complete obstruction of the duodenal lumen, preventing normal passage of gastric contents into the small intestine. This condition occurs in approximately 1 in 5,000 to 1 in 10,000 live births and is strongly associated with Down syndrome (trisomy 21) in about 20-30% of cases.
Duodenal atresia results from failure of recanalization of the solid epithelial cord that normally forms the duodenal lumen during the 8th to 11th weeks of embryonic development. The obstruction most commonly occurs in the second portion of the duodenum, distal to the ampulla of Vater, leading to progressive dilatation of the stomach and proximal duodenum while the distal bowel remains collapsed.
Affected newborns typically present within the first 24-48 hours of life with bilious vomiting (if obstruction is distal to the ampulla), feeding intolerance, and failure to pass meconium normally. The classic radiographic finding is the 'double bubble' sign on abdominal X-ray, showing a dilated stomach and proximal duodenum with absence of distal bowel gas, which confirms the diagnosis and necessitates immediate surgical intervention via duodenoduodenostomy.