PLACENTA AND UTEROPLACENTAL VESSELS 

  1. The Pathology of Trophoblastic Invasion and formation of the placental vessels
  2. The Placenta
  3. Uteroplacental Vessels. The spiral artery, after being breached by the non-villous trophoblast, undergo extensive adaptation and structural changes in order to provide the intervillous space of the enlarging placenta with an adequate amount of maternal blood. This process is complete by 22-24 weeks.
  4. Flow Velocity Waveforms (FVW).
    FVW in uterine arterial vessels in second and third trimester have

indicating that they supply a low resistance vascular system. The RI and PI decrease as the pregnancy progresses in 90% of patients. In < 10% of patients, a variable trend is present.
FVW has an early diastolic notch.

 

 

  1. Uterine Artery Resistance Index (RI)
  2. Uterine artery pulsatility index (PI) (Table)– Rizzo et.al. 1993
  3. Uterine artery pulsatility index (PI) (Graph)– Rizzo et.al. 1993

 

 

 

Video clip of Placental Vasculature (3D )