Readout - What's the difference between vasa previa and funic presentation

Take Home Points

definitions

Funic: Latin for umbilical cord
Funic Presentation: Umbilical cord is the presenting structure
Vasa Previa: Fetal vessels still within the placental membrane cover a portion of the cervix

steps to diagnosis of vasa previa

• Place color Doppler over the cervix
• If you see color, then place a spectral tracing
  • Tracing = mother's heart rate = maternal vessel
  • Tracing = fetal heart rate = fetal vessel

when to think about vasa previa

• I feel it is always reasonable to look for this entity if following up a placenta previa (and in fact we try to always check for color flow on the cervix)
• Other settings when particularly important (whenever vessels "wander off placenta") 
  • ​Velamentous cord insertion 
  • ​​​Succenturiate lobe
  • Not investigating for vasa previa in both of these settings has resulted in malpractice cases that were lost.

Why is this entity so important

• In a vasa previa, the blood inside the vessels is part of the fetal circulation.
  
• During delivery, if one of these fetal vessels ruptures and 100 mL of blood is lost, that is a huge hemorrhage for a newborn (1/3 of their blood volume).
  
• If a maternal blood vessel ruptures and the mom loses 100 mL of blood, there is no clinical significance.
  
• If vasa previa is not diagnosed prior to birth, the fetal death rate has been reported to be as high as 60%.