New observations on the pathogenesis of multiple intestinal atresias.

It has been suggested that multiple intestinal atresias result from multiple ischemic infarctions of the intestinal tract. We have studied surgical material from 59 neonates with intestinal atresias seen at our hospital between 1975 and 1986. Forty (68%) patients had single intestinal atresias and 19 (32%) had multiple atresias. There were seven cases of hereditary multiple atresias seen in three families and 12 cases of nonhereditary multiple atresias. All hereditary cases had numerous type I or type II gastrointestinal atresias but none had type IIIa atresia. Six of the seven hereditary cases had multiple atresias in the small as well as large bowel. The 12 patients with nonhereditary atresias had various types of atresias but mesenteric or intestinal interruption was observed in only two patients. All patients with hereditary multiple intestinal atresias showed identical microscopic appearances in the small and large intestine, consisting of sieve-like multiple lumina, each surrounded by its own mucosa and muscularis mucosae but sharing a common muscle coat. There was no evidence of lanugo, bile pigments, or squames within the lumen distal to atretic segments in any of these patients. Six nonhereditary cases who had multiple septal atresias affecting only the small bowel demonstrated essentially similar lesions on microscopic examination as seen in hereditary cases. There was no evidence of arterial occlusion in the mesentery and lanugo, bile pigments, and squames could not be found distally in the intestinal contents in any of these cases. These pathologic findings suggest that all cases of hereditary multiple intestinal atresias and some cases of nonhereditary multiple intestinal atresias are a consequence of a malformative process of the gastrointestinal tract rather than an ischemic process.