Intraindividual variability of anorectal manometry parameters.

The present study investigates the intraindividual day-to-day variability of anorectal manometry parameters. Manometric studies were performed in twelve healthy volunteers on three different days. A low compliance capillary perfusion system was used. The values measured on day 1 and day 2, as well as those on day 2 and day 3, showed no significant (p greater than 0.05) differences for any parameter in Wilcoxon's test. Mean percentage of differences as a measure for intraindividual day-to-day variation was relatively low for anal resting (mean: 13.5%) and maximal squeeze (17.5%) pressure. However, it was high for the threshold volumes for minimal perception (71.8%) and urgency to defecate (38.5%) during rectal balloon distention as well as for the minimal volume required to abolish recovery of the rectoanal inhibitory reflex (41.2%). We conclude that anal resting pressure and maximal squeeze pressure both are the most stable anorectal manometry parameters in man, at least over a period of a few days.