Retrospective analysis of medical records and individual case review was undertaken at 11 major obstetric hospitals for a 5 year period from July 1992 to June 1997 to investigate rates of vaginal birth after Caesarean section (VBAC), the occurrences of uterine rupture, and the outcomes for mother and infant following rupture.
Total deliveries were 234,015, of which 21,452 or 9.2% were associated with one or more previous Caesarean sections. Within this scar group, 5419 patients or 25.3% were delivered vaginally.
There were 62 cases of significant uterine rupture with no maternal deaths. Perinatal mortality with rupture was 25% and serious maternal complications (usually hysterectomy) occurred in 25% of those with uterine rupture. In women attempting vaginal delivery after a previous lower segment Caesarean section, the uterine rupture rate was estimated at 0.3%, with 0.05% experiencing a perinatal death and 0.05% requiring a hysterectomy.
Although VBAC rates in Australia remain lower than many overseas reported series, rates are increasing. While rupture continues to be associated with serious adverse outcomes, the incidence of rupture during trial of labour is low and appears to be associated with a better outcome than rupture of an unscarred uterus.