Sensitivity and specificity of multichannel surface electromyography in diagnosing fecal incontinence

Assessment of the neurocontrol of the external anal sphincter has long been restricted to investigating patients by invasive tools. Less invasive techniques have been regarded less suitable for diagnosis. The aim was to develop a surface electromyography-based algorithm to facilitate fecal incontinence diagnosis, and to assess its sensitivity and specificity. Data analysis from a single center prospective study. All patients from colorectal surgery office were considered. They underwent a structured interview, a general physical and proctologic examination. Patients with diagnosed fecal incontinence (Fecal Incontinence Severity Index >10) were included into the study group. The control group consisted of healthy volunteers that scored 5 or less and had negative history and physical exam. Both groups underwent the same tests (rectoscopy, anorectal manometry, transanal ultrasonography, multichannel surface electromyography and assessment of anal reflexes). EMG results were analyzed to find parameters that would facilitate fecal incontinence diagnosis. Sensitivity and specificity of surface electromyography, to diagnose fecal incontinence, were assessed. A total of 49 patients were included in the study group (mean age ± SD 58.9 ± 13.8). The control group (n = 49) gender matched the study group (mean age ± SD 45.4 ± 15.1). The constructed classification tree, based on surface electromyography results, correctly classified 97% of cases. Thee sensitivity and specificity of this classification tree, to diagnose FI, was 96% and 98% respectively. The age of women in the control group differs significantly from mean age of other groups. Surface electromyography is an good tool to facilitate diagnosing of fecal incontinence.