Low-lying incompletely bilobate placenta with vasa previa and velamentous insertion of the cord

Francois Manson, MD.

France

Case report

This is a case of a 32 year-old primigravida presenting at 24, 26, and 32 weeks. We discovered a low-lying bilobate placenta with vasa previa and velamentous insertion of the umbilical cord. The fetus was normal. The patient delivered a healthy baby by cesarean section at 36th week of pregnancy.

Image 1: Abdominal ultrasonography showing two lobes of placenta (*). The lobes of the placenta seemed to be low lying particularly in its posterior part (aspect not shown).

Vaginal ultrasonography was then performed.

Image 2: Longitudinal section where the both parts of the placenta (posterior = right*, anterior = left*) appear low-laying. The lower extremity can be seen near the posterior part of the placenta close to the internal os (IO). An incidental funic presentation partially conceals the vasa previa.

Images 3 and 4: Longitudinal gray scale and color Doppler images showing vessel crossing the internal os.

Images 5 and 6: Image 5: Doppler of the vasa previa showing a fetal rhythm (157 bpm). Image 6: an axial plane just above the internal os (note that on this section the left sided placenta doesn’t appear to be bilobate).

Images 7 and 8: Image 7 - 24 weeks; color Doppler image showing the velamentous umbilical vessels. Image 8 - 26 weeks; color Doppler image showing the velamentous umbilical vessels.

Images 9 and 10: Section at the right of the internal os at the level of the lower uterine segment; we can see vessels running between the amnion and the chorion.

Images 11 and 12: Velamentous insertion of the umbilical cord; gray scale and color Doppler images.

Images 13 and 14: Postnatal appearance of the placenta and membranes. Image 13 shows insertion of the umbilical cord to the amniochorionic membranes; and image 14 shows velamentous insertion of the umbilical cord.

Image 15: Postnatal appearance of the placenta and membranes. Fusion of the lower parts of the two lobes of the placenta: this finding hadn"t been recognized during pregnancy, but has been found retrospectively on the sonographic images.