Congenital atresia and stenosis of the small intestine are classified into the four groups. Type I: The obstruction is caused by a membrane or web. Type II: Blind-ending proximal loop connected by a fibrous cord. Type III(a): The atresia ends blindly with no fibrous connecting with a mesenteric defect. Type III(b): “Apple peel-type” atresia consists of a proximal jejunal atresia and the absence of the superior mesenteric artery. Type IV: Multiple-segment atresia.