N MANY OPERATIONS in which colon and/or rectal resection is followed by sphincter-saving anastomosis, such as in Hirschsprung's disease, one of the problems facing the surgeon is the best point at which to divide the mesenteric vessels in order to preserve the blood supply to the distal end of the mobilized bowel. The marginal vessels should certainly be maintained but it was not clear whether the preservation of arcades toward the root of the mesentery would be beneficial or produce a lower-pressure by-pass. COMPARATIVE ANATOMICAL OBSERVATIONS The rabbit was chosen as suitable for the experiment in view of its distal colonic vascular pattern. Although the anatomical features of the large bowel are rather different with a relatively lengthy the vascular supply of the rabbit's is very similar to the one seen in the human from the splenic flexure downward to the as to the inferior mesenteric artery, left colic artery, and sigmoid arteries. The main trunk in the rabbit is called the posterior mesenteric artery (Fig. 1). The resection of roughly the distal half of the rabbit's rectum is, in relation to the ligated vessels, similar to resection of distal third of the left colon, sigmold and down to the anal canal in the human. The rabbit's rectum, like the human colon, has a definite marginal artery giving some justification for comparisons. MATERIAL AND METHODS Ten rabbits were used in the experiment, four males and six females, with an average weight of 2,150 g (I,800 2,850 g): all of them were starved for 24 hr before operation in order to have a reasonably empty rectum, not distended with fecal pellets. The experiments were conducted under general anesthesia induced by intravenous Nembutal and maintained by chloroform inhalation. One animal had a cardiac arrest soon after laparotomy and died after several attempts to massage the heart. The peritoneal cavity was opened by a left paramedian incision: none of the rabbits had visible abdominal abnormality. In four of the animals, the main arterial trunk to the rectum, the posterior mesenteric artery, was divided and ligated with 3-0 silk (Fig. 2A) so as to preserve continuity through the proximal arcades. In the remaining five, all of the vessels branching from the posterior mesenteric artery were individually divided and ligated, leaving intact only the marginal artery (Fig. 2B). A segment of bowel, from the middle of the rectum downward was then resected, extending down as low as possible. Continuity was restored by end-to-end anastomosis in one layer with
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Dec 1, 1999
Akihiro Nabuchi + 2
Open Access