Background: Anal acoustic reflectometry is a new technique of assessing anal sphincter function. Five new variables reflecting anal canal function are measured: the opening and closing pressure, the opening and closing elastance, and hysteresis.
Objective: This study aimed to compare the reproducibility of this new technique, in terms of test-retest and interrater reliability, with manometry, the current standard test of sphincter function.
Design: This is a comparative study of reproducibility between anal acoustic reflectometry and manometry.
Settings: This study was conducted at a university hospital (outpatient clinic and endoscopy unit).
Patients: Twenty-six (21 female) subjects were assessed with both anal acoustic reflectometry and manometry on 2 separate occasions (test-retest reliability) and 22 (16 female) subjects were assessed with both methods by 2 separate investigators (interrater reliability).
Main outcome measures: Reproducibility was assessed according to the Bland-Altman method.
Results: All of the measured novel anal acoustic reflectometry parameters had acceptable mean differences and repeatability coefficients. Comparison of the 2 methods of sphincter assessment (anal acoustic reflectometry vs manometry) was made for measurements taken at rest and during voluntary contraction. There was no significant difference in terms of test-retest reliability between the manometry maximum resting pressure vs the reflectometry opening pressure (P = .57) or manometry maximum squeeze pressure vs the reflectometry squeeze opening pressure (P = .68). No significant difference between methods was found in interrater reliability during assessments at rest (P = .62) and voluntary contraction (P = .96).
Limitations: Anal acoustic reflectometry is limited, as with all tests of anorectal function, in that the device is placed within the anal canal, causing stimulation of sensory and stretch receptors.
Conclusions: Anal acoustic reflectometry has a reproducibility comparable to manometry in terms of both test-retest and interrater reliability. Anal acoustic reflectometry is a promising technique that allows an assessment of anal canal physiology that is not available with manometry.