title: Risk factors for uterine rupture during a vaginal birth after one previous caesarean section: a case-control study.
abstract: OBJECTIVE
  To study risk factors for uterine rupture (UR) in women with one previous caesarean section (CS) undergoing a vaginal birth after CS (VBAC).
  
  
  METHODS
  A nested case-control study was conducted. Baseline characteristics, general obstetric history, details of the previous CS, current delivery and maternal and neonatal outcome were analysed for 41 cases with a UR and 157 controls (no rupture). Data were extracted from 21 Dutch hospitals.
  
  
  RESULTS
  Labour induction was more common in cases than in controls (51% vs. 25% respectively, P=0.001), and in case of induction therapy especially the use of prostaglandins (PGE2) was more frequent in the case group (86% vs. 46%, P=0.014 for cases and controls respectively). Patients with UR had a significantly lower Bishop score (median: 2.0 vs. 4.0, P=0.005) and received more augmentation of labour compared to controls (36% vs. 18%, P=0.010). In the multivariate analysis induction with PGE2 and oxytocin, induction with PGE2 alone, and augmentation of labour were independent variables affecting the occurrence of UR (respectively OR 13.0, CI 2.3-74.2; OR 4.6, CI 1.9-11.3 and OR 2.7, CI 1.2-6.3). Forty-four percent of the ruptures can be explained by induction of labour with prostaglandins+/-oxytocin.
  
  
  CONCLUSIONS
  Having studied baseline characteristics, general obstetric history, details of the previous CS and of the current delivery, we show that no factors other than the use of PGE2 (+/-oxytocin) in response to a low Bishop score, and augmentation of labour with oxytocin are associated with an increased risk for UR in women undergoing VBAC after one previous CS.
authors.affiliation: Department of Obstetrics and Gynaecology, University Medical Centre Utrecht, Utrecht, The Netherlands. c.h.e.weimar@umcutrecht.nl
authors.forename: C H E
authors.initials: CH
authors.lastname: Weimar
authors.forename: A C
authors.initials: AC
authors.lastname: Lim
authors.forename: M L
authors.initials: ML
authors.lastname: Bots
authors.forename: H W
authors.initials: HW
authors.lastname: Bruinse
authors.forename: A
authors.initials: A
authors.lastname: Kwee
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D015232:Dinoprostone / Q000008:administration & dosage / Q000009:adverse effects; D005260:Female; D006801:Humans; D007751:Labor, Induced / Q000009:adverse effects*; D010121:Oxytocin / Q000008:administration & dosage; D011247:Pregnancy; D011446:Prospective Studies; D012307:Risk Factors; D014597:Uterine Rupture / Q000209:etiology*; D016064:Vaginal Birth after Cesarean / Q000009:adverse effects*
chemical_list: D010121:Oxytocin; D015232:Dinoprostone