title: Perineal surface electromyography does not typically demonstrate expected relaxation during normal voiding.
abstract: OBJECTIVE
  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.
authors.affiliation: Department of Reproductive Medicine, University of California San Diego, San Diego, California, USA.
authors.forename: Anna C
authors.initials: AC
authors.lastname: Kirby
authors.forename: Charles W
authors.initials: CW
authors.lastname: Nager
authors.forename: Heather J
authors.initials: HJ
authors.lastname: Litman
authors.forename: Mary P
authors.initials: MP
authors.lastname: Fitzgerald
authors.forename: Stephen
authors.initials: S
authors.lastname: Kraus
authors.forename: Peggy
authors.initials: P
authors.lastname: Norton
authors.forename: Larry
authors.initials: L
authors.lastname: Sirls
authors.forename: Leslie
authors.initials: L
authors.lastname: Rickey
authors.forename: Tracey
authors.initials: T
authors.lastname: Wilson
authors.forename: Kimberly J
authors.initials: KJ
authors.lastname: Dandreo
authors.forename: Jonathan
authors.initials: J
authors.lastname: Shepherd
authors.forename: Philippe
authors.initials: P
authors.lastname: Zimmern
mesh_terms: D004576:Electromyography / Q000379:methods*; D005260:Female; D006801:Humans; D015588:Observer Variation; D017773:Pelvic Floor / Q000294:innervation / Q000503:physiopathology*; D010502:Perineum; D011237:Predictive Value of Tests; D011312:Pressure; D015203:Reproducibility of Results; D018570:Risk Assessment; D012307:Risk Factors; D013997:Time Factors; D016896:Treatment Outcome; D014481:United States; D014521:Urethra / Q000294:innervation / Q000503:physiopathology*; D001743:Urinary Bladder / Q000294:innervation / Q000503:physiopathology*; D014549:Urinary Incontinence / Q000175:diagnosis* / Q000503:physiopathology / Q000601:surgery; D014563:Urodynamics; D013520:Urologic Surgical Procedures / Q000009:adverse effects