Small intestinal submucosa as a graft to increase rectum diameter

The purpose of our study was to assess the biocompatibility of the porcine small bowel submucosa and its ability to increase the rectal diameter compared with a formal transverse coloplasty.

We assigned 36 New Zealand male rabbits to four experimental groups: groups C1 and C2 were treated with transverse coloplasty and groups S1 and S2 were treated with a patch of a porcine small intestine submucosa. We killed the animals in the C1 and S1 groups on the 7th postoperative day, and the animals in the C2 and S2 groups on the 30th postoperative day. We evaluated outcomes on the basis of animal survival, clinical course, anastomosis bursting pressures, morphometric examination, and histologic and immunohistochemical assessment.

Morphometric examination showed a significant increase in colonic diameter in animals in the S2 group. We found no statistical difference regarding anastomosis bursting pressure between the C1 and S1 groups, and the C2 and S2 groups. On the 30th postoperative day, histologic examination showed total epithelium coverage of the grafts, and the immunohistochemical study showed an organized smooth muscular layer covering the graft. The higher concentration of collagen ticker fiber, type I, was seen in the S2 and C2 groups, but there was no statistical difference between them.

The implanted graft proved superior to transverse coloplasty regarding the increase in distal colon diameter. Remarkable regeneration, marked fibroplasia, and epithelium coverage occurred throughout the graft on the 30th postoperative day.