Anorectal physiology in health: A randomized trial to determine the optimum catheter for the balloon expulsion test.

Background: Anorectal manometry (ARM) and balloon expulsion test (BET) are pivotal in investigation of anorectal disorders. There is controversy, however, about normal values and optimum methodology for performing these tests. Our aims were to compare BET using three different balloons and to establish normal values for ARM and BET in health.

Methods: Forty-four female healthy subjects (mean age 56 ± 12 years) underwent ARM, followed by BET which was performed in a private toilet using three different catheters (party balloon, Foley catheter and a commercially available catheter) in a single-blinded randomized order. Outcome measures were time to balloon expulsion and comprehensive measures of anal sphincter function, the push maneuver and rectal sensation.

Key Results: The Foley catheter took longer to expel compared to both party and commercial balloons (both pairwise P < 0.001) with a wider distribution of results (P < 0.001). Ten of 40 healthy subjects could not expel the Foley catheter within 120 seconds. On ARM, older age was associated with lower resting anal sphincter pressure (ρ = -0.3, P = 0.05) and lower anal squeeze pressure (ρ = -0.3, P = 0.05). Having at least one vaginal delivery (compared to none) was associated with lower anal squeeze pressures (P = 0.03) and a smaller difference between cough and squeeze pressures (P = 0.03).

Conclusions & Inferences: A commercial balloon exhibited superior results in vivo compared to the Foley catheter without the concerns of latex allergy and quality control present with the use of a party balloon. Normal values for high-resolution water-perfused manometry have been established and an effect seen for age and parity.