Abstract

Aim: This study aims to evaluate the significance of puborectalis muscle and anal sphincter thickness in the context of anismus.

Methods: We divided participants into three groups: patients with anismus (n=24), patients with pelvic floor dysfunction (PFD) (n=22), and a control group (n=24). On T2-weighted axial images, the thickness and circumference of both puborectalis muscles were measured at the level of the pubic symphysis, and the mean of these measurements was calculated. Additionally, the thicknesses of the external and internal anal sphincters were measured on T2-weighted axial magnetic resonance images at the level of the mid-anal canal, and the mean of these measurements was also calculated. Comparisons between groups were analyzed using ANOVA with post-hoc Tukey-HSD tests. ROC curve analysis was used to assess the diagnostic performance of key measurements, and interobserver agreement was evaluated using intraclass correlation coefficients (ICC).

Results: A total of 70 participants were included in the study, consisting of 24 patients with anismus (41.6% male), 22 patients with PFD (31.8% male), and 24 controls (45.8% male). Puborectalis muscle thicknesses were significantly higher in the anismus group compared to the PFD group, while the mean puborectalis thickness was significantly greater than that of the PFD group but not significantly different from controls. Additionally, the circumference of the puborectalis muscle was lower in the anismus group compared to the PFD group. ROC curve analysis indicated that puborectalis muscle thickness may potentially serve as a predictive marker for anismus, with an area under the curve of 0.667 (p=0.022). Good to excellent interobserver agreement was noted for the various measurements, with ICC values ranging from 0.762 to 0.970.

Conclusion: Our study suggests that puborectalis muscle and external anal sphincter measurements may aid in diagnosing anismus.

Keywords: Anismus, dyssynergic defecation, MR defecography, puborectalis muscle, sphincter

Copyright and license

Copyright © 2025 The Author(s). This is an open-access article published by Bolu İzzet Baysal Training and Research Hospital under the terms of the Creative Commons Attribution License (CC BY) which permits unrestricted use, distribution, and reproduction in any medium or format, provided the original work is properly cited.

How to cite

1.
Buz Yaşar A, Sarıoğlu AE, Türkoğlu S. Magnetic resonance imaging assessment of the puborectalis muscle and anal sphincter in patients with anismus. Northwestern Med J. 2025;5(3):135-44. https://doi.org/10.54307/2025.NWMJ.175

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