title: Does midline episiotomy increase the risk of third- and fourth-degree lacerations in operative vaginal deliveries?
abstract: OBJECTIVE
  To explore the association between midline episiotomy and the risk of third- and fourth-degree lacerations during operative vaginal delivery with either vacuum extractor or forceps.
  
  
  METHODS
  This retrospective cohort study analyzed all operative vaginal deliveries at a university hospital in 1989 and 1990. Univariate analysis of the relationships between perineal lacerations and obstetric variables was performed. Stratified analysis using the relevant variables was used to calculate relative risk (RR) estimates.
  
  
  RESULTS
  Episiotomy, birth weight, and whether the index birth was the first vaginal birth were associated with third- and fourth-degree perineal lacerations. Stratified analysis demonstrated an RR of 2.4 with a 95% confidence interval of 1.7-3.5 for rectal injury with episiotomy, adjusting for parity and birth weight.
  
  
  CONCLUSIONS
  Midline episiotomy is associated with an increased risk of third- and fourth-degree perineal lacerations in operative vaginal deliveries.
authors.affiliation: Department of Obstetrics and Gynecology, University of North Carolina School of Medicine, Chapel Hill.
authors.forename: J T
authors.initials: JT
authors.lastname: Helwig
authors.forename: J M
authors.initials: JM
authors.lastname: Thorp
authors.forename: W A
authors.initials: WA
authors.lastname: Bowes
mesh_terms: D001724:Birth Weight; D015331:Cohort Studies; D015986:Confounding Factors, Epidemiologic; D004841:Episiotomy / Q000009:adverse effects* / Q000379:methods; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D009772:Obstetrical Forceps; D010502:Perineum / Q000293:injuries*; D011247:Pregnancy; D012189:Retrospective Studies; D012307:Risk Factors; D014620:Vacuum Extraction, Obstetrical; D014947:Wounds and Injuries / Q000453:epidemiology