Anal pressures impaired by stapler insertion during colorectal anastomosis- A randomized, controlled trial

PURPOSE: The significance of anal sphincter injury from transanal inserted staplers was studied. A randomized, controlled comparison was made of anore ctal manometry and clinical function after sigmoid colectomy (avoiding nerv e injury from rectal mobilization), anastomosed by either transanal inserte d stapler or biofragmentable anastomotic ring (avoiding anal manipulation). METHOD: Fifty-eight consecutive patients with sigmoid adenocarcinoma were randomly assigned to transanal inserted stapler or biofragmentable anastomo tic ring groups. Anorectal manometry and clinical bowel function assessment were performed by an independent blinded observer before surgery and six w eeks and six months after surgery. RESULTS: At six weeks after surgery, the re was significant impairment of mean anal resting pressures (mean impairme nt, 23 percent; P < 0.001) and physiologic anal length (mean impairment, 31 percent; P < 0.01) in the transanal inserted stapler group (27 completed t he trial), but not in the biofragmentable anastomotic ring group (18 comple ted the trial). Pressures remained impaired at six months. When changes in the anal pressures were compared between groups, the mean anal resting pres sure (P < 0.001) and maximum squeeze pressure (P < 0.01) at six weeks and m ean anal resting pressure at six months (P < 0.01) were significantly more impaired in the transanal inserted stapler group. Postoperative bowel funct ion was not different between the two groups. Postoperative complications w ere similar. In the transanal inserted stapler group one patient died of an astomotic leak sepsis and one had wound infection; in the biofragmentable a nastomotic ring group one patient died of myocardial infarct and one had wo und infection. CONCLUSION: Direct injuries to the internal anal sphincter o ccurred after transanal inserted stapler but not biofragmentable anastomoti c ring anastomoses. Clinical function was not correspondingly affected, pro bably because of the adequate residual rectal reservoir after sigmoid colec tomy.