Predicting the functional result of anastomoses to the anus: the paradox of preoperative anal resting pressure.

Abstract

This article examines the effect of ileal pouch-anal (n = 134) and coloanal (n = 16) anastomoses on resting anal canal pressures in 150 patients. Patients underwent anal manometry before ileal pouch-anal anastomosis (IPAA) and coloanal anastomosis (CAA) and again six weeks after ileostomy closure following these procedures. A water-perfused catheter system with four radial ports was used for manometry, pressures being recorded during both station and continuous pull through. Patients with IPAA were younger than those with CAA (34 years vs. 50 years) and had a different ratio of hand-to-stapled anastomosis (1:2.6 vs. 1.3:1). All CAA patients had had rectal cancer while IPAA patients suffered mainly from ulcerative colitis (n = 114) or familial polyposis (n = 10). The mean preoperative resting pressure for all patients was 79 mmHg (75-87, 95 percent confidence limit) and the mean fall in this pressure after surgery was 25 mmHg (-21 to -29, 95 percent confidence limit). There was no difference in preoperative pressure or fall between handsewn and stapled anastomoses, or between IPAA and CAA. There was a significant relationship between preoperative pressure and change in pressure that held true for all subgroups (change = -0.7 x preoperative pressure + 31, r = 0.69). Analysis of the functional results confirmed that patients with high preoperative pressure are at risk for severe falls after surgery and are not guaranteed a good result. Conversely, patients with low preoperative pressures may actually have an increase with surgery and are not always incontinent. Patients with low preoperative anal resting pressures should not be denied anastomosis to the anus if they are continent.