EP476 - From structure to function: Correlation between anal electromyography, anorectal manometry, and endoanal ultrasound in patients with fecal incontinence

Purpose/Background: Fecal incontinence is a multifactorial condition caused by structural, functional, and neuromuscular alterations of the anal sphincter complex. A comprehensive assessment is essential to identify underlying mechanisms and guide treatment. High-resolution anorectal manometry (HRAM), endoanal ultrasound (EAUS), and anal electromyography (EMG) provide complementary evaluations of pressure, anatomy, and neuromuscular function. This study aimed to correlate EMG, HRAM, and EAUS findings in patients with fecal incontinence to identify combined structural, functional, and neuromuscular dysfunction patterns.

Methods/Interventions: A prospective descriptive pilot study including two patients was conducted at a tertiary referral center for anorectal physiology between September and October 2025. Patients with a clinical diagnosis of fecal incontinence were consecutively included. All underwent a standardized diagnostic protocol consisting of high-resolution anorectal manometry , anal surface electromyography, and three-dimensional endoanal ultrasound.

Results/Outcomes: Two patients with fecal incontinence were evaluated using high-resolution anorectal manometry (HRAM), anal electromyography (MAPLe), and three-dimensional endoanal ultrasound (3D EAUS). Patient 1,HRAM showed normal resting tone but reduced squeeze pressure, indicating external sphincter hypocontractility. EMG revealed preserved basal activity with low-amplitude voluntary contractions and poor endurance, consistent with partial neuromuscular dysfunction. EAUS identified an anterior defect involving both sphincters.Patient 2,HRAM revealed global sphincter hypotonia and reduced squeeze pressures. EMG showed low basal activity with moderate recruitment and adequate endurance, suggesting partial preservation of external sphincter function.

The combined use of high-resolution anorectal manometry, anal electromyography (MAPLe), and 3D endoanal ultrasound provided a comprehensive evaluation of sphincter function. Manometric findings revealed varying degrees of hypotonia and hypocontractility, while electromyography identified neuromuscular impairment and coordination deficits. Correlation among the three modalities allowed distinction between structural and functional mechanisms, highlighting the value of multimodal assessment in characterizing fecal incontinence.

Conclusion/Discussion: The combined assessment with high-resolution anorectal manometry, anal electromyography (MAPLe), and three-dimensional endoanal ultrasound allows a more precise characterization of the mechanisms underlying fecal incontinence. Correlation between pressure profiles, electrical activity, and anatomical integrity provides complementary information to distinguish structural, functional, and neuromuscular components. This multimodal approach enhances diagnostic accuracy, guides personalized therapeutic strategies, and supports the use of EMG as a valuable adjunct in the comprehensive evaluation of anal sphincter dysfunction.

Figure 1
High-resolution anorectal manometry and anal electromyography (MAPLe®) showing reduced squeeze pressures and low-amplitude muscle recruitment, consistent with hypocontractility and partial neuromuscular dysfunction of the external anal sphincter.
Figure 3
High-resolution anorectal manometry and anal electromyography (MAPLe®) showing low resting and squeeze pressures with preserved but reduced-amplitude muscle recruitment, consistent with sphincter hypotonia, global hypocontractility, and partial preservation of external anal sphincter function.