title: The effect of a mediolateral episiotomy during operative vaginal delivery on the risk of developing obstetrical anal sphincter injuries.
abstract: OBJECTIVE
  The objective of the study was to evaluate the frequency of obstetrical anal sphincter injuries (OASIS) in women undergoing operative vaginal deliveries (OVD) and to assess whether a mediolateral episiotomy is protective for developing OASIS in these deliveries.
  
  
  METHODS
  We performed a retrospective cohort study. Maternal and obstetrical characteristics of the 2861 women who delivered liveborn infants by an OVD at term in the years 2001-2009 were extracted from a clinical obstetrics database and were analyzed in a logistic regression model.
  
  
  RESULTS
  The frequency of OASIS was 5.7%. Women with a mediolateral episiotomy were at significantly lower risk for OASIS compared with the women without a mediolateral episiotomy in case of an OVD (adjusted odds ratio, 0.17; 95% confidence interval, 0.12-0.24).
  
  
  CONCLUSIONS
  We found a 6-fold decreased odds for developing OASIS when a mediolateral episiotomy was performed in OVD. Therefore, we advocate the use of a mediolateral episiotomy in all operative vaginal deliveries to reduce the incidence of OASIS.
authors.affiliation: Department of Obstetrics and Gynaecology, Amphia Hospital Breda, Breda, The Netherlands. joeydevogel@gmail.com
authors.forename: Joey
authors.initials: J
authors.lastname: de Vogel
authors.forename: Anneke
authors.initials: A
authors.lastname: van der Leeuw-van Beek
authors.forename: Dirk
authors.initials: D
authors.lastname: Gietelink
authors.forename: Marijana
authors.initials: M
authors.lastname: Vujkovic
authors.forename: Jan Willem
authors.initials: JW
authors.lastname: de Leeuw
authors.forename: Jeroen
authors.initials: J
authors.lastname: van Bavel
authors.forename: Dimitri
authors.initials: D
authors.lastname: Papatsonis
mesh_terms: D000328:Adult; D001003:Anal Canal / Q000293:injuries*; D015331:Cohort Studies; D004841:Episiotomy / Q000379:methods; D005260:Female; D006801:Humans; D015994:Incidence; D016015:Logistic Models; D009426:Netherlands / Q000453:epidemiology; D007744:Obstetric Labor Complications / Q000453:epidemiology / Q000517:prevention & control*; D016017:Odds Ratio; D011247:Pregnancy; D012042:Registries; D012189:Retrospective Studies; D012306:Risk