Risk factors for uterine rupture during a vaginal birth after one previous caesarean section: a case–control study

ObjectiveTo study risk factors for uterine rupture (UR) in women with one previous caesarean section (CS) undergoing a vaginal birth after CS (VBAC).Study designA 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.ResultsLabour 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.ConclusionHaving 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.