Three-Dimensional Anorectal Manometry Enhances Diagnostic Gain by Detecting Sphincter Defects and Puborectalis Pressure

Background: Constipation and fecal incontinence (FI) are common and are often evaluated with anorectal manometry. Three-dimensional high-resolution anorectal manometry (HRAM) is a promising technology; however, implementation has been limited by lack of metrics and unclear clinical utility. Aim: To investigate the diagnostic utility of 3D HRAM compared to 2D HRAM. Methods: Three-dimensional HRAM studies performed from April 2012 to October 2013 were identified and re-interpreted by two blinded investigators examining 3D function. Disagreements were resolved by a third investigator. Puborectalis (PR) visualization, focal defects, and dyssynergy were reported. Differences between groups were analyzed with Fisher’s exact test. Discordance was analyzed with McNemar Chi-square test. Results: Two hundred and twenty-one 3D HRAM studies were identified. Mean age and BMI were 52.2 ± 17.4 and 27.1 ± 7.5 years (81% female, 74% white). Most common indications for 3D HRAM were constipation (65%) and FI (28%). PR function was visualized in 81% (rest), 97% (squeeze), and 73% (strain). PR was visualized less often at rest in FI than constipation (68 vs. 85%, p = 0.007). Defects were identified twice as often in FI than constipation (19 vs. 10%, p = 0.113). Twenty-nine defects (86% anterior) were visualized on 3D HRAM. Inter-reader agreement was moderate for PR function (κ = 0.471), but fair for focal defects (κ = 0.304). Conclusions: PR function and focal defects can be visualized on 3D-HRAM with added diagnostic benefit compared to 2D. Fair inter-reader agreement for focal defects highlights the need for quantitative metrics.