Objective: To estimate the incidence of women with vasa previa in Australia and to describe risk factors, timing of diagnosis, clinical practice, and perinatal outcomes.
Methods: A prospective population-based cohort study was undertaken using the Australasian Maternity Outcomes Surveillance System between May 1, 2013, and April 30, 2014, in hospitals in Australia with greater than 50 births per year. Women were included if they were diagnosed with vasa previa during pregnancy or childbirth, confirmed by clinical examination or placental pathology. The main outcome measures included stillbirth, neonatal death, cesarean delivery, and preterm birth.
Results: Sixty-three women had a confirmed diagnosis of vasa previa. The estimated incidence was 2.1 per 10,000 women giving birth (95% CI 1.7-2.7). Fifty-eight women were diagnosed prenatally and all had a cesarean delivery. Fifty-five (95%) of the 58 women had at least one risk factor for vasa previa with velamentous cord insertion (62%) and low-lying placenta (60%) the most prevalent. There were no perinatal deaths in women diagnosed prenatally. For the five women with vasa previa not diagnosed prenatally, there were two perinatal deaths with a case fatality rate of 40%. One woman had an antepartum stillbirth and delivered vaginally and the other four women had cesarean deliveries categorized as urgent threat to the life of a fetus with one neonatal death. The overall perinatal case fatality rate was 3.1% (95% CI 0.8-10.5). Two thirds (68%) of the 65 neonates were preterm and 29% were low birth weight.
Conclusion: The outcomes for neonates in which vasa previa was not diagnosed prenatally were inferior with higher rates of perinatal morbidity and mortality. Our study shows a high rate of prenatal diagnosis of vasa previa in Australia and associated good outcomes.