Definition

Vasa previa is a condition where the fetal umbilical blood vessels, which are not enclosed in a membrane, cross the cervical opening. During labor, the cervix will open and the amniotic sac will rupture. This condition causes the umbilical blood vessels to also rupture, leading to bleeding. This can result in the fetus losing a lot of blood and can even cause fetal death, as well as complications for the mother.

Vasa previa is rare and is one of the complications during pregnancy. It also causes bleeding during pregnancy and can result in fetal distress due to bleeding.

The incidence of vasa previa is approximately 1 in every 2,500–5,000 deliveries. Additionally, vasa previa often occurs in pregnancies using in vitro fertilization (IVF), about 1 in every 200 deliveries. Fetal mortality due to vasa previa is around 56%–60% if not diagnosed early before delivery.

Therefore, early detection of vasa previa can help reduce fetal mortality and health complications for the mother. If diagnosed early, it can increase fetal survival by 97%. Post-delivery, some babies need care in the neonatal intensive care unit (NICU) to stabilize their condition.

If you also want to know more about other birth complications, such as Placenta Previa, you can read about it here: Plasenta Previa - Understanding, Treatment, Symptoms, And Treatment.

Causes

In general, there are two causes of vasa previa during pregnancy:

1. Vasa previa is caused by umbilical blood vessels inserting into the amniotic sac. Normally, the umbilical blood vessels are located in the center of the placenta. However, in vasa previa, the umbilical cord blood vessels enter the amniotic fluid and leave the center of the placenta, leaving the blood vessels unprotected by Wharton's membrane, which is located in the umbilical cord. Thus, when the amniotic sac ruptures, the umbilical blood vessels within it also rupture.
2. Vasa previa can also occur in a placenta that is divided into two lobes. The umbilical cord connects one lobe of the placenta to the other. If there are umbilical blood vessels that are exposed and unprotected by a membrane crossing between the two lobes of the placenta and located near the uterus, these blood vessels are prone to rupture during labor.

Risk Factor

Risk factors that increase the occurrence of vasa previa include:

• Low-lying placenta in the uterus, near the cervix, or even closing the cervix
• Previous cesarean section history
• Pregnancy using IVF
• Multiple pregnancies (twins or more)
• Previous surgery of the uterine
• Smoking
• Advanced maternal age (over 35 years old)
• Chronic conditions such as diabetes
• History of curettage

Symptoms

Symptoms in the Mother

Vasa previa usually does not cause symptoms until the delivery begins. However, some pregnant women experience mild vaginal pain.

Additionally, there is dark red vaginal bleeding occurring in the second and third trimesters. This condition indicates that the fetus is experiencing oxygen deprivation (hypoxia), causing the blood to appear darker.

Symptoms in the Fetus 

Symptoms in the fetus include a slower heart rate (bradycardia). Since vasa previa does not directly show symptoms, pregnant women should regularly check their pregnancy to detect complications like vasa previa. Early detection of vasa previa can reduce fetal mortality during delivery.

Diagnosis

The diagnosis of vasa previa can be established through an abdominal ultrasound during routine pregnancy check-ups. Vasa previa can be detected between 18 and 26 weeks of pregnancy. In early pregnancy or the first trimester, vasa previa cannot be detected.

If an abdominal ultrasound reveals vasa previa, the doctor will usually recommend a transvaginal ultrasound. This involves inserting a special ultrasound device into the vagina (birth canal) to confirm the abdominal ultrasound findings.

A transvaginal ultrasound can detail the part of the umbilical blood vessels crossing the vagina. Additionally, a Doppler ultrasound may be performed to more clearly depict the umbilical blood flow.

Management

When a doctor diagnoses vasa previa during pregnancy, they will recommend several therapeutic and treatment steps. The doctor will closely monitor the pregnancy to maximize the duration of the pregnancy until the risk of delivery arises.

Overall, the goal of vasa previa therapy and treatment is to safely prolong the pregnancy and deliver the baby early to prevent blood vessel rupture. Here are some management steps that can be taken:

• Non-stress test, involving regular twice-weekly fetal heart rate assessments. This test is safe for the fetus.
• Corticosteroid medication, given to help the fetal lungs develop and mature before a planned cesarean section.
• The doctor may recommend early hospitalization before delivery to closely monitor the mother and fetus.
• Surgery may be performed between 34 and 37 weeks of pregnancy.
• Emergency cesarean section if the amniotic sac ruptures early or the fetus is in distress and there is vaginal bleeding.
• The doctor will explain the risks and benefits of timing the delivery to reduce pregnancy complications associated with vasa previa.
• In vasa previa cases, the doctor may advise avoiding sexual intercourse temporarily.
• These management steps will be based on the pregnancy condition, maternal health history, fetal condition, and other factors.

Complications

The most concerning complication of vasa previa is the rupture of the amniotic sac. This causes the unprotected blood vessels to also rupture, leading to fetal bleeding.

If you are interested in reading more about rupture of membranes, you can read it here: Early Burst Breaks (KPD) - Understanding, Cause, Symptoms, And Treatment.

Undetected vasa previa until delivery increases the risk of vaginal bleeding and fetal distress. Fetal bleeding increases the risk of fetal death due to significant blood loss. Fetal mortality during pregnancy is also very high if vasa previa is not diagnosed until delivery.

Prevention

The risk of vasa previa cannot be prevented. However, routine pregnancy check-ups can help prevent complications arising from vasa previa. Early detection during pregnancy can improve fetal survival.

When to See a Doctor?

If a pregnant woman experiences dark red vaginal bleeding accompanied by mild vaginal pain, she should go to the nearest emergency room for immediate care.

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