Uterine rupture is a rare peripartum complication associated with severe maternal and perinatal morbidity and mortality,1,2 and is one of the most common clinical causes of medical litigation in the developed world.3 Previous caesarean section is the main risk factor for uterine rupture.1,4–6 Because the rate of caesarean section is increasing worldwide, we are dealing with an increasing number of mothers with previous caesarean section, with consequent higher risk of uterine rupture.7 The percentage of uterine rupture after trial of labour (TOL) remains low (<1%),8 with usually favourable maternal and perinatal outcome.1,2 However, dramatic reduction of TOL9 has been observed after reports of a worrying increase in rupture-related serious perinatal outcomes.10,11 This resulted in an increase in the rate of caesarean section and associated short-term and long-term complications.7,8 A meta-analysis found that uterine rupture may be twice as common after TOL than at elective repeat caesarean section.12 The majority of studies compared total TOL with elective repeated caesarean section without looking specifically into ruptures at emergency prelabour caesarean section, and without comparing rupture rates after each of spontaneous and induced labour with elective repeated caesarean section.
Norway has an increasing rate of caesarean section, from 1.8% in 1967 to 17.1% in 2008.13,14 However, there is a relatively high rate of TOL with vaginal births in 51% of mothers with previous caesarean section.15 This gives a good basis for studying uterine rupture among mothers with different starts to birth after previous caesarean section. Such information is available through the Medical Birth Registry of Norway (MBRN) where data about all births are routinely recorded.13
The aim of the present study was to determine the risk factors, percentage and maternal and perinatal outcomes of uterine rupture after previous caesarean section. A further aim was to study the impact of different induction methods on uterine rupture and perinatal outcomes.