Repeatability of anorectal manometry in healthy volunteers and patients

Background: Anorectal manometry is used extensively in the assessment of patients with disorders of the pelvic floor. The present study investigated the repeatability of anorectal manometry in healthy volunteers and patients. Patients and methods: A total of 30 healthy volunteers (15 men and 15 women) and 10 patients with fecal incontinence (4 men and 6 women) underwent perfusion manometry and volumetry. Intraindividual variability was evaluated using the intraindividual correlation coefficient (ICC). Interindividual variability was expressed as the standard deviation from the calculated mean values. Results: We found a high intraindividual correlation for the squeezing pressure (ICC 0.75 e0.95), vector volume (ICC 0.88-0.97), and rectal perception (ICC 0.82-0.98). The anal resting pressure showed moderate repeatability (ICC 0.60-0.72). However, with regard to sphincter asymmetry, rectal compliance, and the rectoanal inhibitory reflex, a wide range of variability was found. In the female volunteers, the squeezing pressure and vector volume were lower than in those in the male volunteers. The anal pressure, vector volume, thresholds for urgency, and the maximum tolerable volume were lower in the incontinent patients than in the healthy volunteers. Conclusions: The squeezing pressure, vector volume, and rectal perception allow a reliable analysis of anal sphincter function. Sphincter asymmetry, rectal compliance, and the rectoanal inhibitory reflex were of limited diagnostic value.