Transient Anal Sphincter Relaxations in Fecal Incontinence: Insights From 3D High-Definition Anorectal Manometry

Fecal incontinence (FI) is a prevalent and multifactorial disorder, often associated with anal sphincter dysfunction. Transient anal sphincter relaxations (TASR) have been proposed as a contributing factor in FI, though their significance remains unclear. This study aimed to assess the prevalence and clinical impact of TASR using high-definition anorectal manometry (3D-HD ARM).

We conducted a cross-sectional study including consecutive FI patients undergoing 3D-HD ARM. TASR was defined as a resting pressure drop below 15 mmHg lasting > 15 s. Manometric parameters, structural assessments, and clinical scores were compared between TASR and non-TASR groups.

Of 62 FI patients (74.2% female, mean age 60 years), TASR was detected in 14.5% (95% CI 0.06-0.25). TASR patients exhibited significantly lower maximum squeeze pressure (68.5 ± 25.6 vs. 105.3 ± 56.1 mmHg, p = 0.004) and reduced anal pressure during cough (54.8 ± 28.5 vs. 85.2 ± 35.9 mmHg, p = 0.019). TASR was also associated with pelvic floor akinesia (p = 0.006) and rectoanal coordination disorders (p = 0.037), though no significant structural differences were observed.

TASR was identified in 15% of FI patients, with associated anal sphincter dysfunction and pelvic floor abnormalities. The use of 3D-HD ARM may enhance TASR detection, suggesting a potential role in FI pathophysiology. Further studies are needed to determine its clinical significance and impact on treatment response, particularly regarding biofeedback therapy.