Vasa previa (VP) pregnancy is a rare but serious obstetric complication where fetal blood vessels are unprotected as they traverse the fetal membranes in the lower uterine segment, lying in front of the fetal presenting part.
Essentially, these fetal blood vessels are vulnerable because they aren't supported by the umbilical cord or placental tissue. This situation poses a significant risk of fetal hemorrhage and fetal death, particularly during labor or membrane rupture. The incidence of vasa previa is reported to be approximately 1 in 2000 to 5000 deliveries.
Understanding Vasa Previa
Here's a breakdown of the condition:
- Fetal Blood Vessels: In a normal pregnancy, fetal blood vessels are either within the umbilical cord or embedded in the placenta.
- Location: In vasa previa, these vessels are located within the membranes covering the cervix, near the internal cervical os (the opening of the cervix).
- Risk: Because the vessels are unprotected, they can rupture when the membranes rupture during labor or even due to pressure from the fetus.
- Consequences: Rupture of these fetal vessels can lead to rapid fetal blood loss (exsanguination) and fetal death if not immediately addressed.
Types of Vasa Previa
There are two main types:
- Type I: Occurs when a velamentous cord insertion is present. In this scenario, the umbilical cord inserts into the membranes rather than directly into the placenta. The fetal vessels then run unprotected through the membranes to reach the placenta.
- Type II: Occurs when the vessels run between lobes of a bilobed placenta or between a placenta and a succenturiate lobe (an accessory lobe).
Diagnosis and Management
Early diagnosis is crucial. Vasa previa can be diagnosed prenatally using ultrasound, particularly with color Doppler. This allows for careful monitoring and planned delivery, typically via cesarean section, to minimize the risk of fetal hemorrhage. Without prenatal diagnosis, the fetal mortality rate can be high.
Key Takeaways:
- Vasa previa is a condition where fetal blood vessels are exposed and unprotected near the cervix.
- It carries a high risk of fetal hemorrhage during labor and delivery.
- Prenatal diagnosis via ultrasound with color Doppler is crucial for improving fetal outcomes.
- Management typically involves planned cesarean delivery.
