Dynamic Functional Luminal Imaging Probe analysis of the anal sphincter opening function during straining in healthy volunteers.

Abstract

Introduction: The objective of the present study was to introduce a novel method assessing anal canal opening in healthy volunteers (HV) using the EndoFLIP^™ system. By analyzing dynamic loops during push maneuver, the study aimed to identify the most reliable markers of anal canal opening function during this maneuver. Methods: Forty HV women were recruited and underwent anal canal assessments with the EndoFLIP^™ system, both at rest and during push maneuver. Cross-sectional area (CSA)-pressure loops were constructed for each HV at distension volumes of 40 mL and 50 mL. Key parameters (pressure and CSA) derived from these loops were identified as potential markers of anal function to reduce dimensionality. Anal opening function during push maneuver was quantified in both percentage (relative variation) and absolute (absolute variation) values for pressure and CSA. Results: The direction of the CSA-pressure loops during push maneuver at 40 mL and 50 mL of distension was upward and to the right, indicating an increase in both pressure and CSA during straining. None of the demographic data were significant predictors of any characteristics of the CSA-pressure loops at 40 mL and 50 mL of distension. The mean relative variation in pressure and CSA at 50 mL of distension and, to a lesser extent, the maximal relative variation pressure and CSA, were identified as markers with the lowest variability. Conclusion: This pilot study points to potential markers for assessing anal opening function during push maneuver. Further confirmatory studies are necessary to establish the clinical utility of these markers.