title: Subsequent pregnancy outcomes after obstetric anal sphincter injuries (OASIS).
abstract: OBJECTIVE
  To describe obstetric outcomes in women with a prior obstetric anal sphincter injury (OASIS) and to identify risk factors for recurrence.
  
  
  METHODS
  A retrospective chart review of women who sustained an OASIS between November 2005 and March 2010 at a tertiary care hospital was performed to identify risk factors for recurrence.
  
  
  RESULTS
  One thousand six hundred twenty-nine patients had an OASIS. Of these, 758 patients (90%) subsequently delivered during the aforementioned timeframe; 685 patients had a subsequent vaginal delivery. Of the women, 3.2% had a recurrent OASIS. Recurrence was associated with larger birth weight (27% ≥4000 g vs 11.6% <4000 g; P = 0.04) and delivery mode (25.0%, 12.5%, and 2.7% for forceps-assisted, vacuum-assisted, and spontaneous deliveries, respectively (P = 0.0001)), whereas a history of fourth-degree laceration, prior wound complication, or episiotomy at subsequent delivery were not (P = 0.5, P = 0.5, and P = 0.4, respectively).
  
  
  CONCLUSIONS
  Recurrent OASIS occurred in a small percentage of women (3.2%) who subsequently delivered vaginally. Recurrent OASIS was associated with operative vaginal delivery and birth weight 4000 g or greater. Neither episiotomy at first delivery nor at subsequent delivery conferred an increased recurrence risk.
authors.affiliation: From the Department of Obstetrics and Gynecology, Feinberg School of Medicine, Northwestern University, Chicago, IL.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Basham
authors.forename: Laura
authors.initials: L
authors.lastname: Stock
authors.forename: Christina
authors.initials: C
authors.lastname: Lewicky-Gaupp
authors.forename: Christopher
authors.initials: C
authors.lastname: Mitchell
authors.forename: Dana R
authors.initials: DR
authors.lastname: Gossett
mesh_terms: D000328:Adult; D001003:Anal Canal / Q000293:injuries*; D001724:Birth Weight; D036861:Delivery, Obstetric / Q000009:adverse effects*; D005242:Fecal Incontinence / Q000453:epidemiology; D005260:Female; D006801:Humans; D010502:Perineum / Q000293:injuries; D011247:Pregnancy; D011256:Pregnancy Outcome; D012008:Recurrence; D012189:Retrospective Studies; D012307:Risk Factors; D014947:Wounds and Injuries / Q000453:epidemiology