INTER-INDIVIDUAL AND INTRAINDIVIDUAL REPRODUCIBILITY OF ANORECTAL MANOMETRY

Background: This study investigates the inter- and intraindividual var iability of normal values and, thus, the reproducibility of anorectal manometry. Materials and Methods: Following a standardized protocol, t hree anorectal manometries were performed 4 h apart on 2 days of inves tigation, with an interval of 4 weeks, in ten healthy volunteers. Meas ured parameters in all 60 manometries were: sphincter length (SL), res ting pressure (RP), maximum squeeze pressure (MSP), relaxation of the internal anal sphincter (RIAS), and rectal compliance (RC). Interindiv idual variability was expressed as standard deviation from calculated mean values and intraindividual variability was tested with Wilcoxon's test for tied samples and Spearman's rank correlation test. Results: A large interindividual variability was found for all measured paramet ers, except for SL, reflecting the extensive absolute range of measure d values. Median intraindividual variability among the six individual measurements and between both measurement days revealed that MSP, RIAS and RC are parameters which were not reproducible in this volunteer s tudy. A significant correlation between the results of the repetitive measurements and, thus, a good reproducibility was only found for the parameters SL and RP. Conclusions: Anorectal manometry has only limite d diagnostic value; although rather exact quantifications of individua l parameters can be achieved, the impact of these measurements should be regarded rather critically, since only SL and RP appeared to be rep roducible parameters.