Objective To assess the anal sphincteric function after intersphincteric resection for low rectal cancer by vectorial manometry. Methods Maximal anal pressure, vector volume, vector symmetric index and rectal anal inhibitory reflex were assessed in 16 patients underwent intersphincteric resection for low rectal cancer from 1999 to 2006. Thirty patients with low anterior resection for rectal cancer and another 30 healthy individuals were selected as control. Results The patients in intersphincteric resection group were subdivided into soiling group and defecation function good group. Maximal pressure, vector volume and vector symmetric index of the patients in soiling group and defecation function good group were significantly lower than those of the healthy and low anterior resection controls (P＜0.001). The maximal systole pressure, systole vector volume and vector symmetric index in soiling group were significantly lower than those in function good group (P＜0.001). The 25.0% patients in intersphincteric resection group had rectal anal inhibitory reflex， was significantly lower than that of the low anterior resection control group (93.3%, P＜0.001). Conclusion The maximal pressure and vector volume are compromised in patients underwent intersphincteric resection . The vectorial manometry can be an objective comprehensive tool for the evaluation of anal sphincter function in patients with intersphincteric resection.
