Motility abnormality in intestinal atresia.

This study was designed to investigate the motility of the small bowel of the lamb under the conditions of experimental intestinal atresia. Of 26 fetal lambs operated upon (50 to 90 days gestation), 13 came to term. All term lambs exhibited a type 3a atresia. Six were successfully repaired and had intestinal myoelectric activity monitored for periods from 2 to 27 hours. A slow wave pattern (12 to 13/min) was present in the bowel of control lambs and in the proximal dilated bowel and the microbowel of atretic lambs, confirming the presence of functional smooth muscle. Spike potentials, which indicated circular muscular contractions, occurred 10% of the time in the control intestine, 5% in the proximal dilated gut (P less than .2), and 0% in the microbowel (P less than .001). A previously undescribed myoelectric transient of variable amplitude and frequency (6 to 24/min) was identified in all lambs studied. Histologic evaluation demonstrated villous hyperplasia in the microbowel and mucosal flattening in the distended bowel. The data suggest that the quiescent microbowel distal to the atresia contributes significantly to the functional obstruction.