Anatomic basis of mesenteric elongation for ileo-anal anastomosis with J-shaped reservoir: comparison of two techniques of vascular section.

Total proctocolectomy followed by ileo-anal anastomosis with a reservoir is the operation of choice for the treatment of familial adenomatous polyposis and of certain forms of hemorrhagic proctocolitis. Vascular section is sometimes necessary to enable the extremity of the reservoir to reach the anal sphincter without traction. The aim of this study was to compare the gain in length obtained by two different techniques of vascular section and to assess in terms of the vascular anatomy of the last small intestinal loop which technique best preserved the vascularisation of the reservoir as a whole. Twenty-two fresh cadavers had an ileal J-shaped reservoir of 18 cm fashioned from the last loop of small intestinal loop after section of the root of the mesentery. The gains in length so obtained were measured after section of the ileocolic a. at its origin (group A) or section between the two vascular arches of the last small intestinal loop (group B); the superior mesenteric vessels were then injected with colored resin. The gain in length obtained by these two methods was identical (2.3 +/- 1.1 cm for group A as against 2.18 +/- 0.9 cm for group B), but only if the section of the ileocolic a. was accompanied by section of the mesenteric peritoneum up to the vascular arch formed by the anastomosis between the terminal branch of the superior mesenteric a. and the ileocolic a. The constancy of this anastomosis always allowed section of the ileocolic a. while preserving good vascular distribution to the entirety of the reservoir. Section between the two arches was difficult when the distance separating them was small.