3 Types of Vasa Praevia (explained)

• Vasa praevia oocurs when one or more of the baby‘s placental or umbilical blood vessels cross the entrance to the birth canal beneath the baby.
• When the cervix dilates or the membrane rupture, the unprotected vessels can tear, causing rapid fetal haemorrhage.
• When the baby drops into the pelvis, the vessels can be compressed, compromising the baby’s blood supply and causing oxygen deprivation.

Source: deseretnews.com

There are distinct types of Vasa Praveia:- 

• Type 1, where there is a velamentous cord insertion (where the umbilical cord attach to the amniotic sac instead of directly to the placenta).
• Type 2, where unprotected fetal vessels run over the cervix (birth canal) between the main placenta and a second placental lobe.
• Type 3, where unprotected fetal vessels exit the placental edge to run through the membrane of the amniotic sac, and then “boomerang” to reinsert into the placental edge at another location. In type 3, there is usually not a velamentous cord insertion, and there is a single placental mass.