What is the optimum methodology for the clinical measurement of resting anal sphincter pressure?

There are conflicting recommendations from consensus groups with regard to the assessment of resting anal sphincter pressure. Our aims were to evaluate and compare the performance of three recognized techniques for the clinical measurement of resting anal sphincter pressure.

In each of 54 patients presenting for anorectal manometry, and suffering from constipation or fecal incontinence, three different techniques for assessment of resting anal pressure were undertaken, namely stationary, stationary pull-through and slow pull-through techniques. Resting anal sphincter pressures were compared between groups and between techniques.

Mean resting anal sphincter pressure was lower with stationary, compared with stationary pull-through and slow pull-through, techniques (P < or = 0.002). Resting pressure was higher for constipation than incontinence regardless of technique used (P < 0.00001). The techniques were highly correlated with each other (P < 0.0001). The stationary pull-through technique conferred a minor advantage in the discrimination between constipation and incontinence. The stationary technique required significantly less time for completion (P < 0.0001).

Resting anal sphincter pressure varies according to the specific technique employed, yet each technique is valid. The stationary pull-through technique confers a minor advantage in clinical discrimination of patients, but the stationary technique is more time-efficient. Standardized anal sphincter testing should be established to enable inter-laboratory comparisons.