title: Fetal head circumference and length of second stage of labor are risk factors for levator ani muscle injury, diagnosed by 3-dimensional transperineal ultrasound in primiparous women.
abstract: OBJECTIVE
  We evaluated rate of levator ani muscle (LAM) avulsion among primiparae using 3-dimensional transperineal ultrasound to identify possible risk factors for such trauma.
  
  
  METHODS
  We conducted a prospective observational study. Three-dimensional transperineal ultrasound was performed on all subjects. Primiparae were evaluated 24-72 hours after vaginal delivery. In all, 32 nulliparous gravidae (35-41 weeks) and 15 elective cesarean delivery primiparae were evaluated as methodological controls. We compared newborn head circumference (HC), birthweight, second stage duration, maternal age, baby sex, episiotomy, and instrumental delivery.
  
  
  RESULTS
  LAM trauma was observed in 39 of 210 (18.8%) patients and no controls. Odds ratio for LAM trauma when newborn HC >or= 35.5 cm was 3.343 (95% confidence interval, 1.33-8.42); when second stage duration >or= 110 minutes, odds ratio was 2.27 (95% confidence interval, 1.07-4.81). Logistic regression showed that HC >or= 35.5 and second stage duration >or= 110 minutes increased odds of LAM trauma by a factor of 5.32.
  
  
  CONCLUSIONS
  Large HC and prolonged second stage duration are risk factors in LAM trauma. Elective cesarean delivery may prevent LAM trauma.
authors.affiliation: Department of Obstetrics and Gynecology, Hadassah-Hebrew University Medical Centers, Jerusalem, Israel.
authors.forename: Dan V
authors.initials: DV
authors.lastname: Valsky
authors.forename: Michal
authors.initials: M
authors.lastname: Lipschuetz
authors.forename: Angelika
authors.initials: A
authors.lastname: Bord
authors.forename: Ido
authors.initials: I
authors.lastname: Eldar
authors.forename: Baruch
authors.initials: B
authors.lastname: Messing
authors.forename: Drorith
authors.initials: D
authors.lastname: Hochner-Celnikier
authors.forename: Yuval
authors.initials: Y
authors.lastname: Lavy
authors.forename: Sarah M
authors.initials: SM
authors.lastname: Cohen
authors.forename: Simcha
authors.initials: S
authors.lastname: Yagel
mesh_terms: D000293:Adolescent; D000328:Adult; D001003:Anal Canal / Q000293:injuries; D036861:Delivery, Obstetric / Q000009:adverse effects; D005260:Female; D006257:Head / Q000033:anatomy & histology / Q000196:embryology*; D006801:Humans; D021621:Imaging, Three-Dimensional; D007748:Labor Stage, Second; D016015:Logistic Models; D018482:Muscle, Skeletal / Q000293:injuries; D009929:Organ Size; D010298:Parity; D010502:Perineum / Q000000981:diagnostic imaging; D049590:Postpartum Period; D011247:Pregnancy; D011446:Prospective Studies; D012307:Risk Factors; D013997:Time Factors; D014463:Ultrasonography; D055815:Young Adult