Perineal surface electromyography does not typically demonstrate expected relaxation during normal voiding

Anna C. Kirby, Charles W. Nager, Heather J. Litman, Mary P. Fitzgerald, Stephen Kraus, Peggy Norton, Larry Sirls, Leslie Rickey, Tracey Wilson, Kimberly J. Dandreo, Jonathan Shepherd, Philippe Zimmern

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


Aims To describe perineal surface patch electromyography (EMG) activity during urodynamics (UDS) and compare activity between filling and voiding phases and to assess for a relationship between preoperative EMG activity and postoperative voiding symptoms. Methods 655 women underwent standardized preoperative UDS that included perineal surface EMG prior to undergoing surgery for stress urinary incontinence. Pressure-flow studies were evaluated for abdominal straining and interrupted flow. Quantitative EMG values were extracted from 10 predetermined time-points and compared between fill and void. Qualitative EMG activity was assessed for the percent of time EMG was active during fill and void and for the average amplitude of EMG during fill compared to void. Postoperative voiding dysfunction was defined as surgical revision or catheterization more than 6 weeks after surgery. Fisher's exact test with a 5% two-sided significance level was used to assess differences in EMG activity and postoperative voiding dysfunction. Results 321 UDS had interpretable EMG studies, of which 131 (41%) had EMG values at all 10 predetermined and annotated time-points. Quantitative and qualitative EMG signals during flow were usually greater than during fill. The prevalence of postoperative voiding dysfunction in subjects with higher preoperative EMG activity during void was not significantly different. Results were similar in the 42 subjects who had neither abdominal straining during void nor interrupted flow. Conclusions Perineal surface patch EMG did not measure expected pelvic floor and urethral sphincter relaxation during voiding. Preoperative EMG did not predict patients at risk for postoperative voiding dysfunction.

Original languageEnglish (US)
Pages (from-to)1591-1596
Number of pages6
JournalNeurourology and urodynamics
Issue number8
StatePublished - Nov 2011


  • electromyography
  • pelvic floor
  • stress urinary incontinence
  • urethra
  • urodynamics
  • voiding dysfunction

ASJC Scopus subject areas

  • Clinical Neurology
  • Urology


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