Understanding Vasa Previa: What Expecting Parents Need to Know

Vasa previa is a rare but serious pregnancy complication that can cause dangerous repercussions for both the mom and the baby. It is essential for the expectant parents to understand its causes, symptoms and treatment options. Not to forget the difference between  vasa previa and placenta previa. Read this blog to understand vasa previa, including its risks, diagnosis, and treatment options, along with ways to reduce the risk of developing the condition. 

Let’s start by understanding what vasa previa is.

What Is Vasa Previa?

Vasa previa is an uncommon–serious pregnancy complication where unprotected fetal blood vessels (Arteries or veins) of the umbilical cord or placenta run across or near the internal opening of the cervix, beneath the baby. These vessels are not protected by the umbilical cord or placental tissue, making them vulnerable to rupture when labour begins. This causes severe blood loss in the baby and may lead to death if it is not identified and treated properly.  ^{1 2}

It is important for to-be parents to understand what vasa previa is. Since the blood vessels are part of the baby’s circulatory system, any damage to these vessels can result in haemorrhage (blood loss due to damaged vessels), putting the baby at immediate risk. Timely diagnosis and appropriate intervention are essential for preventing complications. ³

What Are The Types Of Vasa Previa?

There are two types of vasa previa:

Type I vasa previa: Vasa previa can be caused by velamentous cord insertion, which occurs when the umbilical cord fails to connect properly to the placenta. Instead, the cord's blood vessels flow outside the placenta, leaving them exposed and vulnerable to breakage. If the placenta is located low in the uterus near the cervix, these exposed blood vessels are more prone to rupture during labour as the fetus comes closer to the cervix. ¹

Type II vasa previa: In Type II, the vessels link to an accessory lobe of the placenta rather than the main placenta. This occurs when the placenta has a secondary lobe (called a succenturiate or bilobed placenta), and the connecting vessels traverse the membranes close to the cervix, posing a similar risk of rupture. ¹

Vasa Previa is often confused with Placenta Previa. Let’s now understand the difference. 

What Is the Difference Between Vasa Previa and Placenta Previa?

Although vasa previa and placenta previa are both placental-related disorders, their mechanics and risks of danger differ. Placenta previa occurs when the placenta partially or completely covers the cervix, preventing the infant from passing through the birth canal. A second-trimester low-lying placenta or placenta previa is a risk factor for vasa previa at delivery, even if the low-lying placental location resolves in the third trimester. To avoid problems, birth is frequently performed via caesarean section.  ^{1 4}

In contrast, in vasa previa, the baby's blood vessels cross the cervix rather than the placenta. These vessels are unprotected and extremely susceptible to rupture, resulting in fetal blood loss and demise. Vasa previa and placenta previa should not be confused because they have distinct implications and treatments. While both can cause complications during delivery, vasa previa provides a greater immediate risk to the fetus due to the possibility of blood loss.

How Serious Is Vasa Previa?

Vasa previa is considered a critical pregnancy complication. If undiagnosed and the blood vessels rupture during labour or delivery, it can lead to rapid fetal blood loss. The severity of this condition cannot be overstated:

• Without prenatal diagnosis and proper management, the fetal mortality rate can be as high as 60%
• With early detection and appropriate medical care, the survival rate increases to about 97% ¹ 

Who Is at Risk For Vasa Previa?

There are several factors that increase the risk of having vasa previa. These include ¹:

• Placenta previa or low-lying placenta
• Multiple pregnancies, such as twins or triplets
• In vitro fertilisation (IVF) or assisted reproductive technologies
• A history of uterine surgery, such as a C-section or myomectomy
• Type I vasa previa
• Type II vasa previa
• Second-trimester placenta previa that resolves

While vasa previa is rare, affecting only about 1 in 2,500 pregnancies, these risk factors make it more likely for some women to develop the condition. ²

How Common Is Vasa Previa?

Vasa previa is a rare condition, occurring in approximately:

• 1 in 1,200–1 in 2,500 births.
• Higher incidence in IVF pregnancies (1 in 200)
• More common in multiple pregnancies ¹

Although the condition is uncommon, it poses a significant risk when it does occur, making awareness and early detection crucial.

Symptoms and Causes of Vasa Previa

Most cases of vasa previa don't present obvious symptoms during pregnancy. However, some warning signs may include 1 2:

• Vaginal bleeding (blood is dark red) during the second or third trimester, especially when the membranes rupture
• Abnormal fetal heart rate patterns during labour, as the baby may experience distress due to compromised blood supply

How Is Vasa Previa Diagnosed?

Diagnosis typically involves several methods:

• Transvaginal Ultrasound: which provides a closer look at the cervix and surrounding tissues, is the most effective method for diagnosing this condition. It is done during weeks 18 to 26. ^{1 2}
• Colour Doppler Imaging: is used to identify the presence of fetal blood vessels near the cervix, confirming the diagnosis.

Once vasa previa is identified, the pregnancy will be closely monitored to ensure the safety of both the mother and baby. Early diagnosis is key to preventing complications and planning for a safe delivery.

What Is the Treatment For Vasa Previa?

The treatment for vasa previa primarily involves planning for an early C-section delivery, often between 34 and 37 weeks of pregnancy, before labour begins. This helps avoid the risk of blood vessel rupture during contractions or the water breaking. In cases where vaginal bleeding occurs or the mother goes into labour early, an emergency C-section section may be required to prevent fetal haemorrhage. Hospitalisation may be recommended in the weeks leading up to the scheduled delivery to monitor the mother and baby closely.

Other treatments include: 

• Corticosteroids: to help your baby’s lungs develop in the womb
• Non-stress tests: To check your baby’s heart rate

How Can I Reduce My Risk of Vasa Previa?

There is no guaranteed way to prevent vasa previa, but some steps can be taken to reduce the risk, particularly for women with known risk factors ¹:

• Regular prenatal care: Early and consistent prenatal checkups can help catch placental abnormalities early.
• Ultrasound screening: If you are at higher risk, your healthcare provider may recommend additional ultrasounds to monitor the placenta and umbilical cord development closely.
• Awareness of risk factors: If you have a history of uterine surgery, multiple pregnancies, or IVF treatments, discuss your risk with your doctor early in pregnancy.

What Can I Expect If I Have Vasa Previa?

If you are diagnosed with vasa previa, your doctor will likely recommend:

• Regular monitoring through ultrasounds and possibly hospitalisation in the final weeks of pregnancy
• Scheduled C-section to prevent labour from starting naturally
• Immediate action in case of vaginal bleeding or signs of labour

It’s natural to feel anxious about the diagnosis, but with proper medical care and close monitoring, the risks can be managed effectively.

Does Vasa Previa Affect the Baby?

The baby is mainly impacted by vasa previa because of the possibility of blood vessel rupture and bleeding. However, when diagnosed early and managed properly, the outlook is positive. In most cases, with a planned C-section before labour begins, the baby can be delivered safely with minimal risk. ¹

In Conclusion

Vasa previa is a rare but serious condition that requires early diagnosis and careful management to ensure the health and safety of both mother and baby. Understanding the risks, symptoms, and treatment options can help expectant parents be better prepared and proactive in their prenatal care. With advancements in prenatal imaging, vasa previa can often be detected early, allowing doctors to develop a tailored delivery plan that minimises complications.

If you or someone you know is at risk or has been diagnosed with vasa previa, remember that with the right medical support, a safe and successful delivery is achievable. Always consult with your healthcare provider to understand your options and to receive the best possible care during pregnancy.

FAQs

1. Can vasa previa be diagnosed early?

Yes, vasa previa can often be diagnosed in the second trimester during routine ultrasounds.¹

2. Is vasa previa life-threatening?

Vasa previa can be life-threatening if not diagnosed early, as it can lead to fetal haemorrhage. However, with early diagnosis and proper management, the risks can be minimised. ¹

3. What is the difference between vasa previa and placenta previa?

In vasa previa, fetal blood vessels run near the cervix, while in placenta previa, the placenta itself covers the cervix. ¹

4. How is vasa previa treated?

The primary treatment for vasa previa is a planned C-section, usually between 34 and 37 weeks, to avoid labour. ¹

5. What are the symptoms of vasa previa?

Vasa previa typically does not cause symptoms but may result in vaginal bleeding or abnormal fetal heart rate patterns during labour. ¹