Relationships between the results of anorectal investigations and symptom severity in patients with faecal incontinence

Purpose: Anorectal dysfunction is the focus of diagnostic investigations for faecal incontinence. However, severity of incontinence and anorectal investigation results can be discordant. The aim of this study was to define the relationships between anorectal investigation results and incontinence severity to determine which measures, if any, were predictive of incontinence severity. Methods: Patients presenting for investigation of faecal incontinence completed a symptom questionnaire, anorectal manometry, rectal sensation, pudendal nerve terminal motor latency, and endoanal ultrasound. Bivariate analyses were conducted between the Jorge-Wexner score and investigation results. Subgroup analyses were performed for gender and symptom subtypes (urge, passive, mixed). A multiple regression analysis was performed. Results: Five hundred and thirty-eight patients were included. There were weak correlations between the Jorge-Wexner score and maximal squeeze pressure [r = − 0.24, 95%CI(− 0.31, − 0.16), p < 0.001], and resting pressure [r = − 0.18, (95%CI(− 0.26, − 0.10), p < 0.001]. In men only, there were significant associations between the Jorge-Wexner score and endoanal sonography [IAS defects: t(113) = − 2.26, p = 0.03, d = 0.58, 95%CI(− 4.38, − 0.29)] and rectal sensation (MTV: r_s = − 0.24, 95%CI(− 0.41, − 0.06), p = 0.01). No substantial differences were observed in the urge/passive/mixed subgroup analyses. Multiple regression analysis included three variables: age (β = 0.02, p = 0.17), maximal resting pressure (β = − 0.01, p = 0.28), and maximal squeeze pressure (β = − 0.01, p < 0.01). The variance in the Jorge-Wexner score accounted for by this model was < 10%, (R² = 0.07, p = < 0.01, adjusted R² = 0.06). Conclusion: Anorectal investigations cannot predict the severity of faecal incontinence. This may be due to limitations of diagnostic modalities, the heterogeneity of anorectal dysfunction in these patients, or contributing factors which are extrinsic to the anorectum.