Medica Genetic Center, Gomel, Belarus.

The following images show a case of bilobate placenta with vasa previa diagnosed at 21 weeks of a pregnancy.

Images 1, 2: 21 weeks, transvaginal scans. The image 1 shows sagittal scan of the cervix and lower segment of the uterus with two parts of the placenta localized at the anterior and posterior walls of the uterus. The image 2 shows color Doppler scan at the same level as in the image one. Vascular structures (vasa previa) crossing the inner cervical orifice can be seen. This emphasis the need of the color Doppler imaging of the cervix, because with classical gray scale imaging the vessels were not visible (see the image 1).

Images 3, 4: 21 weeks, transvaginal scans. The images show sagittal color Doppler (Image 3) and spectral Doppler (Image 4) scans of the cervix and lower segment of the uterus with two parts of the placenta localized at the anterior and posterior walls of the uterus. Vasa previa crossing the inner cervical orifice can be seen. The image 4 additionally provides information about fetal heart rate pulsation within the vessels, which differentiates them from maternal vessels within the cervix.

Image 5: The image represents a schematic drawing showing a view on the inner cervical os of the uterus. The drawing explains the situation in cases of vasa previa running between two lobes of the placenta and crossing the inner cervical orifice.