Duration taken for the anal sphincter pressures to stabilize prior to anorectal manometry

Anorectal manometry (ARM) is an integral part of evaluating the anal sphincter function. The current recommendation of waiting for 5 min (lead-in-time) prior to beginning the recording has no evidence. A prolonged procedure may reduce patient compliance.

We analyzed data from 100 consecutive patients who underwent 3-dimensional ARM at a single center. Their pressure studies were analyzed in consecutive 10-s segments, beginning from the time of insertion of the probe into the anal canal. We defined stabilization of the pressure as the absence of a pressure difference among two consecutive 10-s segments. The study population had 31 males. Their mean age was 33.0 years (SD-14.4). The mean time for the pressure to stabilize was 84.2 s (SD-29.5), range 17.2-203.7 s, 95th percentile 136.2 s. Eleven and one participant(s) took longer than 120 and 150 s for the pressure to stabilize, respectively. There was no correlation of sex (Mann-Whitney U test, p = 0.89) and the time to pressure stabilization. Age and the time to stabilize (Spearman rho - 0.246, p = 0.017) showed a weak negative correlation. A lead-in-time of 5 min, as recommended by present guidelines may be unnecessary. Waiting for 150 s/2½ min may be sufficient and will minimize the procedure duration.