Influence of gender and age on anorectal function: normal values from anorectal manometry in a large caucasian population.

INTRODUCTION: In the literature, data on the effects of gender and age on the pressure data of anorectal manometry differ. Possible reasons are investigation of only small numbers of healthy people and comparison of only 2 groups with large age differences. In addition, data about the influence of gender or age on anorectal sensation are sparse. Therefore, the aim of the present study was to determine the influence of gender and age on anorectal manometry in a large healthy female and male cohort spanning a great age range.
METHODS: Anorectal manometry was performed in 72 women and 74 men with a median age of 64 years in both groups (ranges: women 22-90 years; men 23-88 years). We determined mean anal resting and squeeze pressure as well as minimal rectal balloon volume for perception and for urge/desire to defecate. The Mann-Whitney U test was used to analyze for gender differences, regression analysis to search for age influences.
RESULTS: Squeeze pressure (p = 0.007) and perception threshold (p < 0.001) are significantly lower in females, while the mean resting pressure and urge threshold are similar in females and males. Mean resting pressure (women p < 0.0001; men p = 0.03) and mean squeeze pressure decrease (women p < 0.0001; men p = 0.004) with age. An age-related increase in sensory thresholds (= decreased rectal sensitivity) is only seen in females (perception threshold p = 0.01; urge threshold p = 0.04).
CONCLUSION: Most of the parameters measured by anorectal manometry (anal canal pressure, sensory thresholds) are influenced by gender and age. Therefore, the results of anorectal manometry must be interpreted in relation to sex- and age-adapted normal values.