The mucosal response in the excluded limb after jejunoileal bypass for morbid obesity.

Twelve patients underwent a takedown of the jejunoileal bypass with restoration of normal continuity of the intestine. Specimens were obtained for biopsy from the excluded proximal jejunum and distal ileum as well as the distal in continuity jejunum. Hypertrophy of the mucosa was observed in the in continuity segment, as previously described. Villi of the bypassed jejunum displayed no evidence of hypertrophy or of atrophy and were identical in size to villous measurements prior to creation of the jejunoileal bypass. At the ultrastructural level, absorptive cells of bypassed jejunal segments exhibited normal morphologic characteristics. There was no indication of cellular immaturity above the level of the intestinal crypts. In contrast, villi of bypassed ileum, near the colonic anastomosis, demonstrated hypertrophy, presumably reflecting reflux of luminal material into this segment of bypassed intestine. The results of this investigation support the concept that significant morphologic alterations of the mucosa do not occur in totally bypassed segments of intestine after the jejunoileal bypass procedures with attainment of weight stabilization.