Understanding Velamentous Cord Insertion: What Expectant Parents Need to Know

Normally, your umbilical cord attaches to the center of your placenta, providing your baby with a steady flow of nutrients and oxygen. When the umbilical cord doesn’t attach properly, velamentous cord insertion (VCI) can occur, and you’ll need specialized care to prevent delivery complications.

Velamentous cord insertion (VCI) is when your umbilical cord attaches to the membranes surrounding the placenta rather than directly to the center of the placenta itself. Fortunately, it’s rare, affecting around 1% of pregnancies. 1

Usually, the umbilical cord’s blood vessels are protected by Wharton’s jelly—the gelatinous substance that cushions the blood vessels from injury.

However, without a direct insertion, those blood vessels must travel unprotected outside the cord to pass through the membranes and reach the placenta. This increases the risk that they’ll get damaged.

Similarly, another type of abnormal cord insertion—marginal cord insertion—happens when the umbilical cord attaches to the edge of the placenta (within two centimeters of the border). Although distinct from VCI, marginal cord insertion can also cause similar complications. 2

Are you at risk of VCI?

Unfortunately, the exact cause of VCI isn’t fully understood. However, you’re more likely to experience it if you’re carrying twins, especially ones who share a single placenta (monochorionic twins), or if you’re older and pursued in vitro fertilization (IVF) treatment. 1 3

You’re also at risk of an abnormal cord insertion if your placenta lies low in your uterus. 4

Can you prevent VCI?

Unfortunately, you can’t prevent abnormal insertions. 5 However, you’ll have a smoother pregnancy overall by sticking to a healthy lifestyle.

It’s best to catch VCI early. If your doctor finds it, they’ll perform regular screenings to watch out for any complications.

As mentioned, without the protection of Wharton’s jelly, the umbilical cord’s blood vessels are more likely to get injured. Any compression or rupture potentially reduces your body’s oxygen flow to your baby and can lead to hypoxia.

You could also be at a higher risk for birth complications, including preterm delivery, low birth weight, thrombosis (blood clots), or even pregnancy loss. If you have a vaginal birth, you may also have difficulty delivering the placenta. 5

While your doctor will avoid tugging on the umbilical cord to dislodge the placenta, they’ll need to manually remove it or perform a curettage to scoop out the tissue, which puts you at a higher risk of postpartum hemorrhage. 1

You can also be at risk of other complications:

Vasa previa

Sometimes, if you have VCI, you may also develop vasa previa—a condition where unprotected blood vessels in the placenta cross over the cervix or pass close to it.

Vasa previa can complicate your delivery. Typically, the amniotic sac ruptures during labor or childbirth—in a process known as your “water breaking”—allowing your baby to pass through the birth canal. However, if you have vasa previa, this rupture can cause fetal blood vessels to tear. Your baby could bleed to death under these circumstances, so it’s very important your doctor catches it early.

Your doctor will need to perform a C-section rather than have you attempt a vaginal delivery. 6 7

Selective Intrauterine growth restriction (sIUGR)

As outlined above, if you have VCI, the umbilical cord’s blood vessels can get pinched, restricting blood flow.

When you’re carrying twins, this can lead to a condition where one of your babies receives more blood flow than the other, known as selective intrauterine growth restriction (sIUGR).

This condition can affect your pregnancy whether or not your twins share a placenta. However, it’s more common if they do, affecting around 10–15% of monochorionic twin pregnancies. 8

Due to this unequal blood flow, one twin may become malnourished and weigh about 20% less than the other, possibly resulting in death (while still in utero)—which can then affect your healthier baby.

Other health concerns

Unfortunately, the complications from VCI and other abdominal cord insertions make your baby more likely to have a low Apgar score. The Apgar test is an important evaluation that doctors, nurses, or midwives use to determine a newborn’s overall health. 9

Your doctor will perform the Apgar test one minute after birth and again at five minutes to assess your baby’s: 10

• Breathing
• Heart rate
• Muscle tone
• Reflexes
• Skin color

Even if your baby seems healthy, an Apgar screening detects possible health concerns and helps your doctor decide if he needs closer monitoring or further treatment.

You may not experience any symptoms of VCI itself (even if you have it), making it challenging to diagnose VCI during your pregnancy. In some cases, your doctor may discover VCI during a routine ultrasound and then use color Doppler ultrasounds—a more advanced imaging technique—to get a better picture of the umbilical cord insertion site. 5

Usually, your doctor can pinpoint signs of VCI by examining the symptoms and complications caused by it.

For example, VCI leads to vasa previa, which may be suspected if you experience vaginal bleeding while your baby shows signs of distress, such as a concerning heartbeat pattern. 4

Sometimes, your doctor won’t be able to diagnose VCI until after delivery when they can examine the placenta.

There’s no specific treatment to correct VCI. Instead, your doctor will focus on monitoring and managing any complications you develop.

Your doctor will also perform frequent ultrasounds to monitor your baby’s growth and assess blood flow through the umbilical cord vessels.

If you have VCI, the American College of Obstetricians and Gynecologists (ACOG) recommends weekly checks starting from your 36th week of pregnancy. 11

Depending on your circumstances, you may need a planned C-section. Before this, your doctor may give you certain medications to help your baby’s lungs develop (antenatal corticosteroids) when you’re between 28–32 weeks pregnant, and may recommend hospitalizing you at 30–34 weeks.

This stay prepares you for preterm delivery at 34–37 weeks. 4

In some cases, your doctor may decide to treat your vasa previa by using fetoscopic laser photocoagulation (FLP).

This laser clots those naked blood vessels near the cervix, stopping the blood flow and reducing the risk of your baby bleeding out if they rupture. 7 12

While it’s understandably scary to get diagnosed with velamentous cord insertion, your doctor is there to help. Stay informed, attend all your prenatal appointments, and actively participate in your doctor’s management plan to help ensure the best outcome for you and your baby.