Level of anastomosis and anorectal manometry in predicting function following anterior resection for adenocarcinoma

The clinical and physiological consequences of sphincter preservation after resection of rectal carcinoma at various levels were evaluated. Thirty-two patients (mean age 59.2 years; range 31-79 years) who had undergone curative surgery at least one year previously and were not given adjuvant therapy, were studied with 19 normal controls. Three blinded observers independently assessed clinical sphincter function, level of anastomosis (ANL) and anorectal manometry. 85.7% had an increase in stool frequency but their normal lifestyles were unaffected. The mean stool frequency was 3.1 (range 2 to 8) times/day. The anal maximal basal and maximum squeeze pressures, rectal volume of first sensation (VIS) and urge, maximum tolerable volume and compliance were all significantly impaired (P < 0.05). Patients with poorer function had significantly lower ANLs (P < 0.05). On multiple regression analysis, the ANL and the VIS significantly predicted stool frequency (P < 0.05). ANL below 6 cm was significantly associated with impaired frequency of stools (P < 0.05). This may be a subgroup of patients whose residual rectal reservoir function is compromised and may theoretically benefit from colonic pouches.