Prenatal ultrasound diagnosis and prognosis analysis of vasa previa

Objective To investigate the prenatal ultrasonographic features and prognosis of vasa previa, to explore the application value of sector scanning in the intracervical mouth by antenatal ultrasound, then to increase vasa previa detection rate. Methods Prenatal ultrasound images, clinical characteristics and pregnancy outcome of 35 pregnant women with vasa previa confirmed by surgery and pathology were analyzed retrospectively, the diagnostic effectiveness of sector scanning in the intracervical mouth was evaluated. Results Thirty-three of the 35 vasa previa cases were detected by sector scanning in the intracervical mouth, with a detection rate of 94.3% (33/35). Of the 35 cases, 20 cases (60.6%) were first contacted in second trimester and 13 cases (39.4%) were first contacted in third trimester. Two cases were missed or misdiagnosed, which were all first contact in third trimester. Among the 35 cases, 25 were velamentous placenta and 4 were battledore placenta. Twenty cases were low-lying placenta or marginal placenta previa. All 35 women underwent cesarean section. No neonatal mortality, 11 term infants, 20 premature infants of more than 34 weeks and 4 premature infants of less than 34 weeks. All placentas underwent pathological examination after delivery, 4 cases placentas underwent vascular casting, and it was found that 2 cases were vasa previa of umbilical artery branch and 2 cases were vasa previa of allantoic veins branch. Conclusions Vasa previa can be effectively detected by prenatal ultrasonography through sector scanning in the intracervical mouth. Second trimester is the best period to detect vasa previa. Pathomorphological examination on placenta after delivery and vascular casting are helpful to the understanding of vasa previa. Key words: Ultrasonography, prenatal; Vasa previa; Vascular casting