gynecology and obstetrics
Vasa Previa
Diagnosis of Vasa Previa
Transvaginal ultrasonography The diagnosis of vasa previa should be suspected based on presentation or results of routine prenatal ultrasonography. At presentation, the fetal heart rate pattern is usually nonreassuring. The diagnosis is typically confirmed by transvaginal ultrasonography. Fetal vessels can be seen within the membranes passing directly over or near the internal cervical os. Doppler color flow mapping can be used as an adjunct. Vasa previa must be distinguished from funic presentation (prolapse with the umbilical cord between the presenting part and the internal cervical os), in which fetal blood vessels wrapped with Wharton jelly can be seen covering the cervix. In funic presentation, unlike in vasa previa, the umbilical cord moves away from the cervix during ultrasound evaluation; in vasa previa, the cord is fixed in place. 