Time-and Segment-Related Changes of Post-Resected Intestine: A 4 Dimentional Model of Intestinal Adaptation.

OBJECTIVES: To investigate the segment- and time-related changes in rat short bowel syndrome (SBS) and construct a 4D geometrical model of intestinal adaptation. METHODS: Sprague-Dawley rats were divided in 3 groups: 2-day, 7-day and 15-day post-resection groups in which 75% of the jejunoileum was removed. Histological and morphometrical parameters in the remaining proximal to distal intestinal segments, from the jejunum to the distal colon, were comparatively evaluated in the groups. The data were used to construct a 4-dimensional geometric model in which villi were considered as cylinders, and we their surface area was expressed as cylinder lateral area. RESULTS: Major adaptive changes were observed in the ileum consisting of an increase in both the diameter of base and height of villi. A parallel reduction of their number/mm was observed. The resulting ileal architecture was characterized by a limited number of large villi. An opposite pattern was observed in the jejunum whose post-resection structure consisted of an increased number of villi. No changes were observed in the colon. Post-resection restructuring was early and faster in the ileum than jejunum resulting in an increase of absorptive area of 81,5% and 22,5% in the ileum and jejunum, respectively. CONCLUSIONS: Post-resection adaptation is intestinal segment-specific because all major changes occur in the ileum rather than jejunum. Sparing ileal segments during resection may improve the outcome of patients undergoing extensive intestinal resection. Our 4-dimensional model can be used to test interventions aimed at optimizing post-resection intestinal adaptation.