title: Impact of liberal use of mediolateral episiotomy on the incidence of obstetric anal sphincter tear.
abstract: OBJECTIVE
  To assess the impact of liberal compared with restrictive use of mediolateral episiotomy on the incidence of obstetric anal sphincter tear (OAST).
  
  
  METHODS
  Data between the years 1999-2001 (era 1) when liberal mediolateral episiotomy was applied were compared with the years 2004-2008 (era 2) when restricted mediolateral episiotomy was implemented. Liberal mediolateral episiotomy was done for fetal or maternal indications, while restrictive mediolateral episiotomy was done when a tear was imminent. Primary outcome was the incidence of OAST.
  
  
  RESULTS
  A total of 25,170 women who delivered vaginally were included. After adjusting for potential confounders, the incidence of OAST was found to be significantly higher in era 2 (0.4 %) compared to era 1 (0.1 %), (p = 0.02; adjusted OR 2.23; 95 % CI, 1.16-4.29). Among primiparous women, the incidence of mediolateral episiotomy was 71.8 and 27.1 % in eras 1 and 2, respectively (p < 0.001), and the incidence of OAST was 0.2 and 1 % in eras 1 and 2, respectively (p = 0.009; adjusted OR 4.15; 95 % CI, 1.42-12.10). Among multiparous women, the incidence of OAST did not differ significantly (p = 0.52). Returning to the liberal policy among primiparous women only, 124 deliveries are needed to prevent one OAST.
  
  
  CONCLUSIONS
  Liberal compared to restrictive use of mediolateral episiotomy may be a sphincter-saving procedure among primiparous women.
authors.affiliation: Department of Obstetrics and Gynecology, Emek Medical Center, 18101, Afula, Israel.
authors.forename: Noah
authors.initials: N
authors.lastname: Zafran
authors.forename: Raed
authors.initials: R
authors.lastname: Salim
mesh_terms: D000328:Adult; D001003:Anal Canal / Q000293:injuries*; D004841:Episiotomy / Q000009:adverse effects*; D005260:Female; D006801:Humans; D007744:Obstetric Labor Complications / Q000209:etiology*; D011247:Pregnancy; D012189:Retrospective Studies; D017695:Soft Tissue Injuries / Q000209:etiology; D055815:Young Adult