Classification
Type 1: membranous atresia with intact mesentery
Type 2: blind end with intact mesentery
Type 3a: blind end with defect in mesentery
Type 3b: “apple peel” or “Christmas tree” appearance of bowel as it corkscrews around
blood vessel
Type 4: multiple atresias
Duodenal Atresia
Duodenal atresias are thought to be due to failur of canalization of the duodenal
lumen. Obstruction of the duodenum may be due to a number of causes. There could
be a complete disconnection with blind ending segments of the duodenum. There could
be a complete membrane in the duodenal lumen (Type 1) or a perforated membrane
(“windsock anomaly”). 85% of duodenal atresias are distal to the ampulla of Vater.
Other causes of duodenal obstruction in a newborn include annular pancreas,
preduodenal portal vein. Notably, malrotation with volvulus can also cause duodenal
obsruction. If the initial KUB shows a “double bubble sign” (air in the stomach and
proximal duodenum) and scattered gas pockets distally, malrotaion with volvulus should
be ruled out (upper GI series).
The presence of an annular pancreas or preduodenal portal vein may not cause
an obstruction that is clinically significant. If there is an obstruction at level, it is
bypassed with a duodenoduodenostomy. If these congenital anomalies are present,