Prenatal Ultrasound Diagnosis Of Vasa Previa

ObjectiveTo improve the detection rate and accuracy rate in prenatal ultrasound diagnosis of vasa previa.Material and methodsAnalysised 26 vasa previa cases diagnosised by prenatal ultrasound from January 2011 to December 2015 in our hospital.Summarized the high risk factors;Analysised ultrasonic features of vasa previa in cord-placenta insert section and cervix of the uterus;Used Two-dimensional,Color,Power and Spectrum Doppler ultrasound jointly.To contrast surgical results and placental pathology with prenatal ultrasonography.Summarized their prenatal ultrasound diagnostic clues,and analyzed the reason of prenatal missed diagnosis and misdiagnosis.Results1)22 out of 26 cases were correctly diagnosised by prenatal ultrasound.2 cases misdiagnosised,1 case was misdiagnosed as funis presentation,1 case was misdiagnosed as rupture of placental marginal sinus,the follow-up of the patient with placental marginal sinus rupture showed the presence of the vasa previa.2 cases were missed-diagnosised.2)24 out of 26 vasa previa cases were type 1(Univalent placenta with vasa previa),Among which there were 15 cases(3 Twin cases)combined with velamentous placenta,accounting for 62%(15/24).Low-lying placenta or placenta previa 7 cases,accounting for 29%(7/24).2 cases were battledore placenta,accounting for 8%(2/24).2 out of 26 vasa previa cases were type 2(placenta lobata with vasa previa),among which there were 2 cases combined with accessory placenta,0 case with lobulated placenta.3)26 vasa previa cases were accompanied by at least 1 high risk factor.All cases occurred with abnormal placenta;3 out of 26 cases combined with twin and multiple pregnancy(3/26),accounting for 12%(3/26);2 cases with IVF twins,accounting for 8%(2/26);9 fetals with Intrauterine growth restriction,accounting for 35%(9/26);23 out of 26 cases combined with irregular vaginal bleeding,accounting for 89%(23/26);15 vasa previa cases with fetal distress revealled by fetal heart monitoring,accounting for 66%(15/26).4)26 cases were confirmed by clinical,25 out of 26 fetals survivaled by elective cesarean section.1 vasa previa case with velamentous placenta missed diagnosised by prenatal ultrasound,fetal death by vaginal delivery.Conclusion1)Through the observation of cord-placenta insert section?cervix of the uterus,and superimposed using Color?Enegy and Spectrum Doppler technique,prenatal ultrasound can accurately diagnose vasa previa and type it.The characteristics of the vasa previa in this group:(1)The two-dimensional gray scale:It is supported that at least one circle or tubular echoless go across or nearby the mouth of the uterus,with the thin walland and permanent position,pass through before the fetal membranes.In this group,22 out of 26 cases show this feature diagnosed by prenatal ultrasound during the second trimester.(2)Power and Color Doppler ultrasonography:It is used in the third trimester especially bacause vasa previa is indicated by the two-dimensional gray scale intangibly.The inner part of the cervix is shaded by fetal presentation,which can not be clearly displayed.Power Doppler display low-speed blood flow competitively,in order to reduce missed-diagnosised cases,we recommend it,but to be confirmed by Spectrum Doppler ultrasonography.(3)Spectrum Doppler ultrasonography:To confirm that spectrum come from umbilical artery.2)In order to reduce the missed-diagnosised cases of prenatal ultrasound scan,we must pay attention to vasa previa cases with high risk factors during the second trimester and third trimester.Screening pregnant woman in the second trimester,detector should observe cervix of the uterus specially.Transabdominal ultrasound indicated vasa previa faintly shoud be replaced by transperineal ultrasound and transvaginal ultrasound.Transvaginal Color Doppler ultrasound can make a clearer picture compared with transabdominal ultrasound,and do not increase fetal distress and vaginal bleeding of pregnant women,can be used for high risk population as the preferred method of screening during the third trimester.3)Vasa previa is fatal to the fetus.In order to improve the prognosis of perinatal infants,the key are to diagnose as early as possible,strengthen the management and education of pregnant women with high risk factors,elective cesarean section delivery.The use of targeted ultrasound screening for pregnant women with high risk factors is confirmed to be important for clinical.