Role of resting pressure gradient in the investigation of idiopathic fecal incontinence

One-third of patients who suffer from idiopathic fecal incontinence are found to have maximum mean resting pressures within the normal range. The objective of this study was to determine whether measuring the gradient of pressure at rest throughout the anal canal is a more sensitive predictor of incontinence in these patients. Anorectal physiology measurements were retrospectively reviewed in patients referred over an 18-month period. Two patient groups were selected for the study: Group 1, continent patients (n = 80); and Group 2, patients with idiopathic fecal incontinence (n = 47). Maximum resting pressures, vector volumes, and resting pressure gradients were all contrasted, sensitivities and specificities were calculated, and receiver operating characteristic curve analyses were performed. Reproducibility studies were also performed for the calculation of the pressure gradient. Patient demographics were similar in the two groups. The resting pressure gradient, maximum mean resting pressure, and vector volumes were significantly lower in incontinent patients compared with the normal patients (P < 0.0001, all comparisons). The sensitivity (and specificity) of resting pressure gradient, maximum mean resting pressure, and vector volumes were 89 percent (96 percent), 55 percent (98 percent), and 53 percent (88 percent), respectively. The resting pressure gradient is the most accurate in detecting fecal incontinence. The authors conclude that this test is simple, reproducible, and identifies an abnormality in the majority of patients with idiopathic fecal incontinence.