title: Racial differences in the structure and function of the stress urinary continence mechanism.
abstract: OBJECTIVE
  To compare the structure and function of the urethral sphincter and the urethral support in nulliparous black and white women.
  
  
  METHODS
  Eighteen black women (mean age 28.1 years) and 17 white women (mean age 31.3 years) completed this cross-sectional study. The following assessments were made: urethral function using multichannel cystometrics and urethral pressure profilometry, pelvic muscle strength using an instrumented speculum, urethral mobility using the cotton-swab test and perineal ultrasound, and pelvic muscle bulk using magnetic resonance imaging.
  
  
  RESULTS
  Black women demonstrated a 29% higher average urethral closure pressure during a maximum pelvic muscle contraction (154 cm H(2)O versus 119 cm H(2)O in the white subjects; P =.008). Although not statistically significant, black women had a 14% higher maximum urethral closure pressure at rest (108 cm H(2)O versus 95 cm H(2)O; P =.23) and a 21% larger urethral volume (4818 mm(3) versus 3977 mm(3); P =.06). In addition, there was a 36% greater vesical neck mobility measured with the cotton-swab test (blacks 49 degrees versus whites 36 degrees; P =.02) and a 42% difference in ultrasonically measured vesical neck mobility during a maximum Valsalva effort (blacks = -17 mm versus whites -12 mm; P =.08).
  
  
  CONCLUSIONS
  Functional and morphologic differences exist in the urethral sphincteric and support system of nulliparous black and white women.
authors.affiliation: Department of Obstetrics and Gynecology, University of Michigan Health Systems, Ann Arbor, Michigan, USA. denhow@umich.edu
authors.forename: D
authors.initials: D
authors.lastname: Howard
authors.forename: J O
authors.initials: JO
authors.lastname: Delancey
authors.forename: R
authors.initials: R
authors.lastname: Tunn
authors.forename: J A
authors.initials: JA
authors.lastname: Ashton-Miller
mesh_terms: D000328:Adult; D044383:Black People; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D010388:Pelvis / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000502:physiology*; D011312:Pressure; D014463:Ultrasonography; D014521:Urethra / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000502:physiology*; D014550:Urinary Incontinence, Stress / Q000208:ethnology* / Q000503:physiopathology; D014636:Valsalva Maneuver; D044465:White People