title: Operative vaginal delivery and midline episiotomy: a bad combination for the perineum.
abstract: OBJECTIVE
  The purpose of this study was to determine the impact of operative vaginal delivery (forceps or vacuum) and midline episiotomy on the risk of severe perineal trauma.
  
  
  METHODS
  In this retrospective cohort study, we assessed the impact of maternal and obstetric factors on the risk of development of severe perineal trauma (third- and fourth-degree perineal lacerations) for all singleton, vertex vaginal live births (n = 33,842) between 1996 and 2003.
  
  
  RESULTS
  Among nulliparous women, 12.1% had operative vaginal delivery, 22.4% had midline episiotomy, and 8.1% experienced severe perineal trauma. Among multiparous women, 3.4% had operative vaginal delivery, 4.2% had midline episiotomy, and 1.2% experienced severe perineal trauma. Controlling for maternal age, ethnicity, birth weight and head circumference, evaluation of the interaction of episiotomy and delivery method revealed that forceps (nulliparous women: odds ratio [OR] 8.6, 95% CI 6.5-10.7; multiparous women: OR 26.3, 95% CI 18.1-34.5) and episiotomy (nulliparous women: OR 4.5, 95% CI 3.7-5.4; multiparous women: OR 14.6, 95% CI 10.4-20.5) were consistently associated with the increased risk of anal sphincter trauma. In fact, the magnitude of effect of the statistically significant synergistic interaction was evidenced by more than 3-fold excess of risk of using operative vaginal delivery alone.
  
  
  CONCLUSIONS
  The use of operative vaginal delivery, particularly in combination with midline episiotomy, was associated with a significant increase in the risk of anal sphincter trauma in both primigravid and multigravid women. Given the reported substantial long-term adverse consequences for anal function, this combination of operative modalities should be avoided if possible.
authors.affiliation: Department of Obstetrics and Gynecology, Wayne State University, Detroit, MI, USA.
authors.forename: Bela
authors.initials: B
authors.lastname: Kudish
authors.forename: Sean
authors.initials: S
authors.lastname: Blackwell
authors.forename: S Gene
authors.initials: SG
authors.lastname: Mcneeley
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Bujold
authors.forename: Michael
authors.initials: M
authors.lastname: Kruger
authors.forename: Susan L
authors.initials: SL
authors.lastname: Hendrix
authors.forename: Robert
authors.initials: R
authors.lastname: Sokol
mesh_terms: D000328:Adult; D001003:Anal Canal / Q000293:injuries*; D004841:Episiotomy / Q000009:adverse effects*; D005113:Extraction, Obstetrical / Q000009:adverse effects*; D005260:Female; D006801:Humans; D015994:Incidence; D022125:Lacerations / Q000453:epidemiology*; D016015:Logistic Models; D007744:Obstetric Labor Complications / Q000453:epidemiology*; D009772:Obstetrical Forceps; D010502:Perineum / Q000293:injuries*; D011247:Pregnancy; D012189:Retrospective Studies; D012307:Risk Factors