Can we perform a prenatal diagnosis of vasa previa to improve its obstetrical and neonatal outcomes?

Abstract

Introduction: Vasa previa (VP) is defined as a condition in which the fetal blood vessels, unsupported by the placenta or the umbilical cord, run through the membranes of the lower uterine segment. It is associated with a high risk of stillbirth by exsanguination. This study aimed to assess the clinical context of diagnosis of VP in order to elaborate a strategy for its prenatal diagnosis and to improve its obstetrical and neonatal outcomes.

Material and methods: This historical cohort study covered the period from January 1, 2011 to December 31, 2015. All women who gave birth at our obstetrics and gynecology department (level 3 university hospital) and who had a VP were included.

Results: Eight cases of VP among 18,152 deliveries were observed (0.04%). Transvaginal sonography (TVS) with color Doppler allowed a prenatal diagnosis of VP in all cases. The mean gestational age at diagnosis was 26 weeks. Placental abnormalities were noted in 7 cases (87.5%) as bipartita or low-lying placenta. In one case (12.5%), the placenta appeared normal while umbilical cord insertion was velamentous. In 2 cases (25%), concomitant placental and cord abnormalities were objectified. The mean gestational age at delivery was 37±2.1 weeks. Seven deliveries (87.5%) had been by caesarean sections, except one, which occurred by vaginal route at 33 weeks of gestation (twin pregnancy). No case of perinatal death was observed.

Discussion: Prenatal diagnosis of VP during screening ultrasounds appears easy to perform and can improve obstetrical and neonatal outcomes. For this purpose, TVS with color and pulsed Doppler remains essential, particularly when an anomaly of the umbilical cord insertion and/or placental location is diagnosed.

Keywords: Placenta previa; Prenatal diagnosis; Transvaginal Doppler sonography; Vasa previa; Velamentous umbilical cord insertion.