Determining the shape of the turns-amplitude cloud during anal sphincter quantitative EMG

William (Tom) Gregory, Amanda L. Clark, Kimberly Simmons, Jau Shin Lou

Research output: Contribution to journalArticle

11 Scopus citations


We aimed to compare our normative data for quantitative interference pattern (IP) analysis of the anal sphincter to previously published data. In 28 nulliparous women, we performed IP analysis during quantitative concentric needle electromyography (QEMG) of the anal sphincter. At each sampling site, a 500-ms epoch was analyzed. The data were log transformed. Linear regression lines (with 95% confidence intervals) were calculated from the log transformed variables "turns-second" and "amplitude-turn." These confidence intervals were then transformed back into the original parameters to yield scatterplots with confidence curves. The mean turns-second were 203 (SD 174). The mean amplitude (mcv)-turn was 266 (SD 87). The regression coefficients for the log-transformed variables are constant=1.5, slope=0.3, and resultant cloud of raw data has a convex upper boundary. These appear slightly different than previously published reports, potentially influencing the determination of normal and abnormal studies.

Original languageEnglish (US)
Pages (from-to)971-976
Number of pages6
JournalInternational Urogynecology Journal and Pelvic Floor Dysfunction
Issue number7
Publication statusPublished - Jun 2008



  • Anal sphincter
  • Electromyography
  • Turns-amplitude analysis

ASJC Scopus subject areas

  • Urology
  • Obstetrics and Gynecology

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