Test-retest repeatability of anorectal physiology tests in healthy volunteers

This study was undertaken to evaluate repeatability of tests of anorectal function in 58 healthy female volunteers, mean age 50 (range, 45-57) years. Participants were studied on two separate occasions by one investigator in one laboratory using the same equipment. Mean difference for perineal position was 0.1 (95 percent confidence interval, -0.1-0.3) cm, and for perineal descent it was 0.02 (-0.2-0.3) cm. For anal mucosa electrosensitivity, mean difference was -0.1 (-0.4-0.1) mA, for maximum anal resting pressure it was 2.2 (-3.5-7.8) cm H2O, for maximum anal squeeze pressure it was -1 (-6.5-4.5) cm H2O, and for pudendal nerve terminal motor latency it was 0.04 (-0.02-0.09) msec. Coefficients of variation varied from 8 percent for pudendal nerve terminal motor latency to 49 percent for perineal descent. There was no systematic variation in repeated measurements for any of the parameters studied; however, the nonsystematic variation was generally large.