Racial differences in pelvic floor muscle thickness in asymptomatic nulliparas as seen on magnetic resonance imaging-based three-dimensional color thickness mapping

Keith T. Downing, Lennox P. Hoyte, Simon K. Warfield, Alison C. Weidner

Research output: Contribution to journalArticle

8 Scopus citations


Objective: The objective of the study was to compare levator and obturator thickness between asymptomatic black and white nulliparas using three-dimensional (3D) magnetic resonance imaging (MRI) color mapping. Study Design: 3D color-mapped MRI of pelvic muscles were evaluated in 22 similar nulliparas (12 black, 10 white). Levator and obturator (OI) were divided into right and left. Levator was subdivided into puborectalis (PR) and ileococcygeus (IC) portions. Maximal thickness of each muscle was recorded and compared between groups. Nonparametric testing was applied, with significance at P = .05. Results: Levator thickness was significantly greater in blacks bilaterally (median right PR, 8.5 vs 6.0 mm; P = .001; right IC, 6.5 vs 4.5 mm; P = .002; left PR, 9.5 vs 5.75 mm; P = .0002; left IC, 6.5 vs 5.75 mm; P = .02). Obturator thicknesses were similar (right OI, 20.0 vs 19.5 mm; left OI, 19.25 vs 19.25 mm; P = NS). Conclusion: Significantly thicker levators but similar obturators were seen in black nulliparas, compared with white nulliparas. These levator differences may influence pelvic floor dysfunction risk. The clinical significance of these findings is under study.

Original languageEnglish (US)
Pages (from-to)625.e1-625.e4
JournalAmerican journal of obstetrics and gynecology
Issue number6
Publication statusPublished - Dec 2007



  • levator ani morphology
  • magnetic resonance imaging
  • pelvic floor dysfunction
  • pelvic floor muscles
  • race
  • three-dimensional

ASJC Scopus subject areas

  • Obstetrics and Gynecology

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