Methodologic Validation of a Faster Pelvic Floor Test: Two Randomized Studies in Anal Acoustic Reflectometry

Anal acoustic reflectometry investigates the opening and closing function of the anal canal using reflected sound waves to measure a cross-sectional area at different pressures. Anal acoustic reflectometry is reliable and repeatable, distinguishes between continence and incontinence and between subgroups of incontinence, correlates with symptom severity, and does not distort the anal canal during investigation.

The purpose of this study was to validate anal acoustic reflectometry methodology by asking 2 questions: can anal acoustic reflectometry be used alongside manometry (order study) and can anal acoustic reflectometry be performed faster (filling study). The secondary aim was to assess the response of the anal canal to stretch using anal acoustic reflectometry.

This research included 2 prospective randomized studies.

The study was conducted at a tertiary referral center.

Patients undergoing investigation for fecal incontinence were included.

For the order study, patients were prospectively randomized to anal acoustic reflectometry, manometry, 2-minute rest and then manometry, anal acoustic reflectometry, or vice versa. For the filling study, patients were prospectively randomized to fast rate anal acoustic reflectometry (5 cm H2O/1 s), manometry, 2-minute rest and then manometry, normal rate anal acoustic reflectometry (5 cm H2O/3 s), or vice versa.

The primary outcome was no difference in anal acoustic reflectometry or manometry variables. Demographic and clinical data were recorded.

The order study included 30 patients with a median age of 63 years (range, 30-84 y); 77% were women. No difference was found among all of the variables of anal acoustic reflectometry and manometry regardless of which test was performed first. The filling study included 50 patients with a median age of 62 years (range, 30-78 y); 80% were women. No difference was found between fast and normal rates of anal acoustic reflectometry and manometry in any order.

This study was limited by its comparison with water-perfused manometry.

Anal acoustic reflectometry and manometry can be performed at the normal or fast rate of anal acoustic reflectometry in any order. A fast rate of anal acoustic reflectometry did not augment the response of the anal canal to stretch as measured by anal acoustic reflectometry and manometry. This study validates a faster anal acoustic reflectometry technique and vindicates previous data. See Video Abstract at http://links.lww.com/DCR/A821.