What is Velamentous Placenta?

Velamentous placenta is an abnormal insertion of the umbilical cord into the placenta.

Normally, the umbilical cord connects to the placenta within its boundaries. In velamentous placenta, the umbilical cord branches before reaching the placenta, and the vessels are only covered by fetal membranes, lacking the protective Wharton's jelly (gelatinous tissue between the amniotic membrane and blood vessels). Its appearance somewhat resembles a sail.

Why Does Velamentous Placenta Occur?

The exact cause is unknown.

Currently, there is no clear medical explanation for velamentous placenta, so no definitive prevention methods exist.

It occurs more frequently in twin pregnancies than in singleton pregnancies. The incidence is approximately 1% in singleton pregnancies but can be as high as 15% in monochorionic twin pregnancies (identical twins).

Additionally, factors such as vaginal bleeding during pregnancy, advanced maternal age (over 35), or chronic maternal conditions may contribute to its occurrence.

What to Do If Diagnosed with Velamentous Placenta During Pregnancy?

Velamentous placenta, an abnormal umbilical cord insertion, is typically diagnosed via ultrasound during prenatal checkups. No specific treatment is required during pregnancy, but close monitoring of the fetus, umbilical cord, and placenta is essential.

• Regular Ultrasounds

  • Monitor Placental Changes

    After detecting velamentous placenta, the doctor will assess the relationship between the umbilical cord, placental vessels, and the cervical os. If vessel branches from the umbilical cord cross the cervical os, it indicates "vasa previa," requiring extra caution.

    The cervical os is the first "gate" the baby passes during delivery. If umbilical vessels block this path, rupture or compression during labor may lead to severe bleeding, fetal hypoxia, or life-threatening risks for both mother and baby.

    Doctors will provide guidance, and mothers must follow recommendations, including possible cesarean delivery if vaginal birth is unsafe. Since umbilical cord position changes during pregnancy, regular ultrasounds are necessary for dynamic monitoring.

  • Track Fetal Growth

    Ultrasounds also evaluate fetal development. The umbilical cord supplies oxygen and nutrients, so velamentous placenta may cause intrauterine growth restriction (IUGR).

    Mothers should have ultrasounds every 4–6 weeks to monitor fetal growth and detect IUGR early, allowing timely medical intervention if needed.

• Monitor Fetal Movements and Seek Immediate Care for Abnormalities

With velamentous placenta, the unsupported umbilical vessels are prone to twisting or compression, risking fetal hypoxia. Mothers should track fetal movements and seek medical help if abnormalities occur.

• Seek Immediate Care for Bleeding or Contractions

Velamentous placenta increases the risk of fetal ischemia and antepartum bleeding, especially during labor. Mothers should go to the hospital immediately if they experience bleeding or frequent, regular contractions in the third trimester.

However, not all cases require cesarean delivery. Many women can deliver vaginally after professional assessment by a doctor.