Quantitative anal sphincter electromyography in primiparous women with anal incontinence

Objective: The purpose of this study was to determine whether evidence of denervation/reinnervation of the external anal sphincter is associated with anal incontinence symptoms immediately after delivery. Study Design: After a first vaginal delivery, 42 women completed an anal incontinence questionnaire. They also underwent concentric needle electromyography of the external anal sphincter. For each subject, motor unit action potential and interference pattern parameters were determined. Results: For the motor unit action potential, no difference was observed between patients with and without anal incontinence symptoms (t-test). For the interference pattern, the amplitude/turn was greater in subjects with fecal urgency (318 ± 48 [SD] μV) and fecal incontinence (332 ± 48 μV), compared with those without fecal urgency (282 ± 38 μV) and fecal incontinence (286 ± 41 μV; P = .02, t-test). Conclusion: In this group of postpartum women with mild anal incontinence symptoms, interference pattern analysis shows evidence of denervation and subsequent reinnervation.