Age-stratified diagnostic value of high-resolution anorectal manometry in women with severe rectocele: interactions between anal relaxation rate and maximum anal resting pressure.

Purpose: This study aimed to assess the diagnostic accuracy of combining anal relaxation rate (ARR) and maximum anal resting pressure (MARP), measured by three-dimensional (3D) high-resolution anorectal manometry (HR-ARM), in identifying high-risk phenotypes of severe rectocele in women (SRW) aged ≥ 50 years compared with healthy female volunteers (HFVs).

Methods: This retrospective comparative study was conducted at the Tianjin Union Medical Center (2018-2024) and included 50 SRW scheduled for surgery and 40 age-matched HFVs aged ≥ 50 years. Log-linear regression was used to assess interaction effects, and the Hosmer-Rothman additive model evaluated qualitative and quantitative interactions. Diagnostic accuracy was assessed using receiver operating characteristic curve analysis.

Results: The concurrent elevation of ARR and MARP (R₁₁ phenotype) was an independent risk factor (P < 0.01), surpassing the diagnostic value of individual parameters. Interaction analysis showed improved diagnostic accuracy, achieving a sensitivity of 82.0%, specificity of 100.0%, area under the curve of 0.82, Youden index of 0.82, odds ratio of 6.14, and 95% confidence interval of 2.19-17.17. Defecography-based classification with SRW-concomitant diseases may be identified using 3D HR-ARM phenotypes, whereas the reverse diagnostic pathway is not feasible. The integration of these modalities holds promise for guiding evidence-based personalized treatment strategies.

Conclusions: Age-stratified 3D HR-ARM analysis of ARR and MARP interactions may help identify high-risk R₁₁ phenotypes in SRW, providing enhanced diagnostic specificity. The R₁₁ phenotype identified in the preoperative X-ray defecography classification for SRW holds the potential for informing tailored therapeutic strategies.