title: The appearance of levator ani muscle abnormalities in magnetic resonance images after vaginal delivery.
abstract: OBJECTIVE
  To describe the appearance and occurrence of abnormalities in the levator ani muscle seen on magnetic resonance imaging (MRI) in nulliparous women and in women after their first vaginal birth.
  
  
  METHODS
  Multiplanar proton density magnetic resonance images were obtained at 0.5-cm intervals from 80 nulliparous and 160 vaginally primiparous women. These had been previously obtained in a study of stress incontinence, and half the primiparas had stress incontinence. All scans were reviewed independently by at least two examiners blinded to parity and continence status.
  
  
  RESULTS
  No levator ani defects were identified in nulliparous women. Thirty-two primiparous women (20%) had a visible defect in the levator ani muscle. Defects were identified in the pubovisceral portion of the levator ani in 29 women and in the iliococcygeal portion in three women. Within the pubovisceral muscle, both unilateral and bilateral defects were found. The extent of abnormality varied from one individual to the next. Of the 32 women with defects, 23 (71%) were in the stress incontinent group.
  
  
  CONCLUSIONS
  Abnormalities in the levator ani muscle are present on MRI after a vaginal delivery but are not found in nulliparas.
authors.affiliation: University of Michigan, Ann Arbor, Michigan 48109-0276, USA. delancey@med.umich.edu
authors.forename: John O L
authors.initials: JO
authors.lastname: DeLancey
authors.forename: Rohna
authors.initials: R
authors.lastname: Kearney
authors.forename: Queena
authors.initials: Q
authors.lastname: Chou
authors.forename: Steven
authors.initials: S
authors.lastname: Speights
authors.forename: Shereen
authors.initials: S
authors.lastname: Binno
mesh_terms: D000328:Adult; D036861:Delivery, Obstetric; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D009130:Muscle, Smooth / Q000473:pathology*; D017773:Pelvic Floor / Q000473:pathology*; D011184:Postoperative Period