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


METHODS
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).


CONCLUSIONS
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.
Department of Obstetrics and Gynecology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA.
Keith T
KT
Downing
Lennox P
LP
Hoyte
Simon K
SK
Warfield
Alison C
AC
Weidner
D000328:Adult; D044383:Black People; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D008279:Magnetic Resonance Imaging; D009132:Muscles; D017773:Pelvic Floor / Q000502:physiology*; D044465:White People