Rupture of the Pregnant Uterus: The Evidence from this Decade on Risk Factors, Predictability and Prognosis

Abstract

Objectives: to identify the incidence of risk factors for and the tools to predict and diagnose uterine wall disruptions. To elaborate on the perinatal and maternal prognosis and on the future reproductive potential of patients who suffered uterine wall disruptions.Method: this is a comprehensive review of the evidence published over the past decade in the English language. Publications were retrieved through Medline search, categorized as to topic and evaluated as to quality of evidence.Results: in contrast to the incidence of uterine rupture in the developing world, the incidence in the developed world is low (0.04%). Grand multiparity, dysfunctional labour and fetal malpresentations remain the major risk factors for uterine wall disruption in the unscarred uterus. Undertaking a trial of labour in the previously scarred uterus is identified as the major risk factor for uterine rupture. Evidence supports the recommendation of a cautionary and highly selective approach to the use of oxytocin to correct dysfunctional labour at any phase, and in the use of prostaglandin for ripening the cervix and induction of labour. Use of epidural anaesthesia, fetal macrosomia, type of lower uterine segment scar (vertical or horizontal) and previous Caesarean section for cephalopelvic disproportion do not seem to be important risk factors. Evidence is lacking as to the safety of trials of labour in multifetal pregnancies. Past history of a previous vaginal birth after Caesarean section (VBAC) seems to be reassuring. Sonography emerges as having a role in evaluating the potential for uterine rupture in labour. Use of partographs in labour could help to reduce the risk of uterine rupture. The most consistent sign of uterine wall disruption in labour is a non-reassuring fetal heart pattern, the severity of which seems to correlate well with the degree of disruption and fetal expulsion. Expediting delivery within 18 minutes of a non-reassuring fetal heart rate pattern carries a good neonatal prognosis, but maternal reproductive potential, while possible, will become guarded.Conclusion: while rare, uterine wall disruption may carry high rates of perinatal morbidity and mortality and maternal morbidity. In the past decade, risk factors have been better defined, with trials of labour after a previous Caesarean section being the most prominent of the risk factors. Overzealous advocacy of such trials cannot be supported. Trials of labour after previous Caesarean section need to be undertaken on a selective basis. Evidence is needed about the safety of trials of labour when certain conditions prevail, including those pertaining to the use of oxytocin, prostaglandin, trials involving patients with more than one previous Caesarean section, and the multifetal pregnancy. Sonography and partographs seem to have potential roles as tools that might help in the selection of candidates for a safe trial of scar and identify women at increased risk for uterine wall disruption.