Incomplete recanalization of the duodenal lumen in intrauterine life causes duodenal stenosis instead of atresia. Stenosis may be due to a stricture or be caused by an intraluminal diaphragm. Associated with annular pancreas, preduodenal portal vein and malrotation. The time of clinical presentation is variable. Severe lesions present in the neonatal period with bilious vomiting. Can see a "Double Bubble" sign on plain film, but not with this patient secondary to stenosis instead of atresia.
Occurs 1 in 10,000 births and in 8% of fetuses with Down syndrome (as in this case).