Mismanaged Vasa Previa Can Cause Birth Injuries Such As Hypoxic Ischemic Encephalopathy (HIE) & Cerebral Palsy

Normally, fetal blood vessels in the umbilical cord connect the infant to the central region of the placenta. Vasa previa is a condition in which these vessels migrate out of the umbilical cord and into the membranes that lie across the opening of the birth canal.

Because of their position, these vessels are at risk of rupturing during labor and delivery. If the fetal blood vessels do rupture, it can lead to massive fetal blood loss and birth injury. Mothers with a diagnosis of vasa previa typically should receive a recommendation for an early scheduled C-section delivery.

What is Vasa Previa?Vasa Previa

In a healthy pregnancy, the baby’s blood vessels travel within the umbilical cord and insert into the central region of the placenta. The umbilical cord protects these vessels. Vasa previa is a condition in which fetal vessels are exposed, running through the amniotic sac membranes and across the opening of the birth canal.

Risk Factors for Vasa Previa

Risk factors for vasa previa include:

  • Pregnancies resulting from in-vitro fertilization (IVF)
  • Multiple gestation (i.e. twins, triplets, etc.)
  • Low-lying placenta or placenta previa (even if it corrects itself)
  • Maternal history of D&C (dilation and curettage) or uterine surgery

Causes of Vasa Previa

There are two main causes of vasa previa:

    1. Velamentous cord insertion: The umbilical cord fails to insert into the appropriate part of the placenta, instead attaching to fetal membranes. The fetal vessels can still connect to the placenta, but must do so without the protection of the umbilical cord.
    2. Multilobe placenta: Sometimes, the placenta is divided into two or more parts, called “lobes.” The fetal vessels connect the lobes together, but have to venture outside of the umbilical cord, putting the infant at risk.

At the time of delivery, vasa previa becomes dangerous to the fetus. As the cervix contracts, the amniotic sac membranes burst (commonly referred to as the “water breaking”). Because the fetal vessels are intertwined with the membranes, they may also rupture, resulting in massive blood loss: in some cases, over 50% of the baby’s total blood volume.

How is Vasa Previa Diagnosed and Managed?

When vasa previa is present, the baby’s health depends on a timely diagnosis. Due to the risk of sudden and severe bleeding if the vessels rupture, a C-section delivery is almost always necessary.

During prenatal visits, physicians use ultrasounds to check for significant problems with the major vessels involved in uteroplacental circulation, including those in the umbilical cord. As early as the 16th week of pregnancy, vasa previa can be detected by a transvaginal ultrasound coupled with use of color Doppler.

Vasa previa that is present during the second trimester may resolve over time. Usually, though, vasa previa persists and the vessels are at risk of rupturing.

Once vasa previa is diagnosed, care standards dictate that the mother should have nonstress tests performed twice a week, beginning at 28 to 30 weeks of gestation, to look for any evidence of umbilical cord compression. Due to the increased risk of preterm delivery, a steroid called betamethasone should be given between 28 and 32 weeks of gestation to help the baby’s lungs and other tissues mature. In addition, the mother should be admitted to the hospital between weeks 30 and 32 for more frequent fetal heart rate monitoring. At this point, nonstress tests should be performed 2 to 3 times a day. A scheduled C-section is typically indicated at about 35 weeks of gestation.

In cases of vasa previa, an emergency C-section delivery should be performed if any of the following occur:

  • Labor
  • Premature rupture of the membranes (PROM)
  • Nonreassuring fetal heart tracings, especially repetitive variable decelerations not helped by medications given to suppress labor (tocolytics)
  • Vaginal bleeding accompanied by nonreassuring fetal heart tracings such as a fast heart rate (tachycardia) or a sinusoidal heart rate pattern, or evidence of pure fetal blood

Unfortunately, vasa previa may  go undiagnosed if proper testing is not performed and diagnosis made. Vasa previa should be suspected when a woman bleeds at the time of membrane rupture. If a baby’s heart rate is non-reassuring, a C-section delivery must occur within a matter of minutes to prevent major damage.

When vessels rupture, it is critical that members of the medical team quickly order blood products for the baby in case a transfusion is needed after C-section delivery.  Transfusions are often life-saving when a baby is affected by vessel rupture caused by vasa previa.

Long-Term Outcomes

Many infants die during birth as a result of vasa previa. Surviving babies are at high risk for serious conditions such as:

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The information presented above is intended only to be a general educational resource. It is not intended to be (and should not be interpreted as) medical advice. If you have questions about vasa previa, please consult with a medical professional.