Purpose: Maximum resting and squeeze pressures have been the most widely employed parameters for manometric assessment of the anal sphincters. However, a single maximum value may not always be the best assessment.
Methods: The aim of this study was to compare mean and maximum resting and mean and maximum squeeze pressures in a large sample population. All manometric pressure profiles were reviewed by a single individual blinded to the patient's age and diagnosis.
Results: Four hundred sixty-six patients with a measurable high-pressure zone were included in this study. The study population was comprised of 279 females and 186 males. A significant difference was found between mean (56.26 mmHg) and maximum (79.2 mmHg) resting pressures (P < 0.01) and also between mean (81.25 mmHg) and maximum (119.50 mmHg) squeeze pressures (P < 0.01). A significant difference (P < 0.01) was also observed when compared by length of the high-pressure zone.
Conclusion: The measurement, documentation, and reporting of mean resting and mean squeeze pressures provide a better perspective of anal manometric results, since the two sets of values are significantly different (P < 0.01), regardless of the anal canal length. Therefore, these data support the standardized evaluation of both mean and maximum pressures in individual patients and in published series.