Functional Assessment of Anal Sphincter with Transperineal Ultrasound and Its Relationship to Anal Continence

Background/Objectives: Anal incontinence is linked to pelvic floor dysfunction. Diagnosis involves assessing both the function and structure of the anorectal unit. Although transperineal ultrasound has gained attention as a less invasive option, its effectiveness as a diagnostic tool for evaluating the relationship between structure and function is still debated. This study aimed to explore the relationship between quantitative measurements of anal sphincter and pelvic floor structures as well as the subjective symptoms and objective assessments of sphincter function regarding anal incontinence. Methods: 50 women with pelvic floor dysfunction were recruited for the study. The severity of anal incontinence was assessed using the CACP score. Ultrasound imaging was employed to measure anal sphincter area, while sphincter pressures were evaluated through manometry. The relationships between variables were analyzed using Pearson's and Spearman's correlation tests. Results: The mean anal sphincter area was 5.51 cm2 at rest and 4.06 cm2 during maximal contraction. Resting anal sphincter pressure had an average of 46.29 mmHg, and contraction pressure averaged 103.25 mmHg. No significant correlation was found between the anal sphincter area and pressure at rest (r = 0.018) or during contraction (r = -0.210). However, a moderate correlation was observed between the change in sphincter pressure and area during contraction (r = 0.312). The CACP score showed no significant correlation with the sphincter area at rest (r = -0.084) but was weakly correlated during contraction (r = -0.270). Conclusions: Conventional diagnostic tools for evaluating anal incontinence can be uncomfortable and are not always readily available. Perineal sonography presents a promising, less invasive alternative for dynamic assessment of the anal sphincter.