High-Resolution Manometry Anorectal Manometry

Purpose: High-resolution manometry (HRM) defines esophageal motility more precisely than standard manometry. This study was undertaken to evaluate anorectal motor function with HRM, and to compare it to standard manometry. Methods: Patients presenting for abnormalities of pelvic floor function were studied with a new high-resolution anorectal manometry catheter and Manoscan (Sierra Scientific, Los Angeles, CA). At the distal tip of the catheter are 2 circumferential solid-state pressure sensors over which a balloon is fitted. 10 cm proximal to these sensors is an array of 10 circumferential solid-state pressure sensors spaced at 7mm on center. the catheter was positioned so it spanned the entire length of the anal canal. Manometries were reviewed in 2 forms: the contour plot of HRM and standard line plots. This allowed direct comparison of the 2 analytical techniques. Results: Manometric maneuvers performed were resting anal canal pressure, squeeze pressure, simulated defecation, and rectoanal inhibitory reflex. Resting pressure was greatest at the beginning of the study and dropped to a baseline. Catheter movement initiated a reflex increase in anal canal pressure. During the squeeze maneuver, pressure increased in the resting high pressure zone (HPZ), and in the sensors cephalad to the resting HPZ. With simulated defecation, anal canal pressure may increase, decrease or remain static. During this maneuver HRM detects pelvic floor movement that appears as normal relaxation with standard ARM. Rectal balloon distention decreased anal canal pressure in a volume-dependent manner. This relaxation started on the cephalad side of the HPZ and progressively extended across the sphincteric segment. Conclusions: HRM provides information that is not easily gleened from standard manometry. The increase in pressure just cephalad to the resting HPZ during the squeeze maneuver likely represents recruitment of the puboprectalis. Progressive relaxation across the anal sphincter during the rectoanal inhibitory reflex may be important for sampling. HRM identifies artifacts introduced by movement of the catheter or the pelvic floor that are not easily discerned with standard manometry.