Anal sphincter competence in healthy women: clinical implications of age and other factors

Normal variation in anal sphincter competence was examined with anal pressure profilometry, using a low compliant recording system and a perfused catheter, in 49 healthy women with a mean age of 51 years (range 20-79). Maximum resting anal pressure and maximum squeeze pressure declined with age (r = -0.61; P less than .001 for both), more rapidly so after menopause. Rectal pressure increased with body mass index (r = 0.60, P less than .001). Closing pressure (ie, the difference between maximum resting anal pressure and rectal pressure), an important determinant of anal continence, was more markedly reduced with age (r = -0.69, P less than .001) than was maximum resting anal pressure. Age-related changes were found for the length of the anal canal (r = -0.36, P less than .05). Parity and anal pressures were unrelated. Women are more frequently affected by anal incontinence than are men. Anal pressure profilometry is a useful diagnostic aid, though age-related changes must be taken into consideration when evaluating the results. The more rapid decline of anal pressures after menopause might imply that anal sphincter tissue is a target for estrogen.