Vasa Previa: Signs, Causes and Treatment


Pregnancy is an important and beautiful phase of a woman’s life. Carrying a baby is not an easy job, a woman learns many things during pregnancy. She matures and become responsible. Pregnancy leads to many changes in a woman’s body. Sometimes these changes can be complicated. One such complication Vasa Previa is discussed below.

Vasa Previa is a rare and severe complication of pregnancy which is defined as a condition where fetal blood vessels run across or nearby the opening of the uterus. There is a major risk of rupturing of these blood vessels along with supporting membranes because these are not supported by the umbilical cord or placental tissue.

vasa previa ultrasound

In This Article:

All You Need to Know About Vasa Previa

Symptoms of Vasa Previa

As such no symptoms are seen and furthermore it goes undetected till labor, a time when the fetus is either distressed or following to be a stillbirth. It is a medical emergency if a woman experiences any painless vaginal bleeding. During vasa previa, thick dark burgundy red blood is seen coming out of the vagina. This is due to the fact that fetus blood carries lower amount of oxygen as compared to mother blood. Therefore, the color of blood coming out of the vagina is dark, then this indicates that it has surely come out from the fetus, not from the mother.


Causes and Risk Factors of Vasa Previa

The most common cause of vasa previa is an umbilical cord abnormality known as velamentous cord insertion. This occurs when the umbilical cord goes inside the membranes they result in unprotected vessels entering the placenta. The second common cause is the bilobed placenta, here the placenta is seen in two pieces. In the above cases, blood vessels are unprotected while crossing the two lobes of the placenta.

Risk of developing vasa previa is more if :

  • Mother has low lying placenta also known as placenta previa
  • She earlier had a cesarean delivery
  • Pregnancy was due to in vitro fertilization (IVF)
  • She has undergone uterine surgery
  • Or she is pregnant with multiple babies.

Diagnosis of Vasa Previa

Transvaginal scan along with color Doppler is the best investigatory method for vasa previa. It is an internal scan, here a transducer producing certain ultrasound waves is fitted inside the mother’s vagina. It is often lubricated and covered by a sheath. It is much better than the abdominal scan as it clearly allows the sonographer to see the area of abnormality.

It is not easy to clearly identify the image on a grayscale. Therefore, color Doppler is required. This helps the technician to clearly see and analyze the speed of the blood flow. Since the disorder is rare there is no routine screening for it. But if given above risk factors are seen doctors recommend a test to confirm the disorder.


Treatment for Vasa Previa

Vasa Previa cannot be prevented but can be diagnosed before the delivery with proper management which increases the survival chances of the baby. There are cases in which the disorder resolves itself during the pregnancy. Once confirmed with vasa previa, the mother needs to have regular follow up ultrasounds to control the condition accurately.

The basic aim is to ensure a safe and progressive pregnancy. The doctor needs to help the mother out in balancing the risk of early delivery with the risk of labor and rupture of membranes. Sometimes the doctor even recommends hospitalization during the third trimester for close monitoring and rest. Pelvic rest is usually suggested, this simply implies that no external object should be placed in the vagina and intercourse is to be avoided. Steroids can also be given to mature the baby’s lungs in premature delivery. It is the doctor’s job to analyze the mother’s ultrasounds and risk factors for planning a safe and proper delivery.

In the case of vasa previa, cesarean delivery is recommended between 35 and 37 weeks of gestation which is due to the fact that the membranes rupture spontaneously and would rupture the baby’s blood vessels also leading to severe bleeding from the baby. Here the doctor should be ready with a team ready with blood transfusion equipment. If one of the vessels tears off, the surgeon can immediately clamp the cord to minimize the amount of blood loss by the baby.


Vasa previa as such do not cause any risk to the mother but the risk is significantly high for the baby. Many times the case of vasa previa goes undetected and result in stillbirth but if detected early it can be diagnosed and survival of the baby is possible. The main thing to focus is on the unusual symptoms related to the disorder and diagnose the disorder as soon as possible.