Rectal Motility in Patients With Idiopathic Fecal Incontinence: A Study With Impedance Planimetry

INTRODUCTION: Most patients with fecal incontinence have poor anal sphincter function. In patients with idiopathic fecal incontinence no structural abnormality can be identified. The aim of the present study was to compare rectal motility patterns in patients with idiopathic fecal incontinence and in healthy controls. METHODS: Rectal impedance planimetry provides simultaneous measurement of rectal pressure, anal pressure, and rectal cross-sectional area at 5 levels. This allows highly detailed description of rectoanal motility. In 12 female patients with idiopathic fecal incontinence (mean age, 64.5) and 12 healthy controls (mean age, 47; 12 females) rectal phasic activity and tone were studied at a distension pressure 10 cm H2O above basic rectal pressure for one hour during fast and one hour after the meal. RESULTS: The median rectal cross-sectional area during fast was 3178 mm(2) (range, 1905-4095) in patients with fecal incontinence and 2907 mm2 (range, 1832-4195) in the control group (P = 42). The postprandial decrease in rectal cross-sectional area was significantly more pronounced in patients (median postprandial reduction 462 mm2 (range, 3124 reduction to 7 increase)) than in the control group (median postprandial change 33 mm2 (range, 844 reduction to 974 increase)) (P = .007). The number of anal sampling reflexes during fast was reduced in patients (P = .03) and rectal wall tension during anal sampling reflexes also tended to be lower (P = .07). No differences in other phasic rectal motility patterns were found. CONCLUSION: Idiopathic fecal incontinence is associated with enhanced postprandial increase in rectal tone and a reduced frequency of anal sampling reflexes.