Circumvallate Placenta: Causes, Symptoms & Pregnancy Complications

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Circumvallate placenta is an uncommon variation in the shape of the placenta. The placenta is an important organ that develops during pregnancy and provides oxygen and nutrients to the growing baby.

In a circumvallate placenta, the placental tissue and membranes have an unusual shape, with the edges folding back toward the fetal surface. This can sometimes be associated with pregnancy complications, although not every woman with this finding will develop problems.

If you have been told that you have a circumvallate placenta, it does not necessarily mean that something will go wrong with your pregnancy. Your doctor will consider the ultrasound findings along with your symptoms, the baby’s growth and the overall progress of your pregnancy.

What is Circumvallate Placenta?

A circumvallate placenta is a type of placental abnormality in which the chorionic plate, which is the fetal side of the placenta, is smaller than the basal plate. As a result, the placental membranes fold back around the edge of the placenta, forming a raised, thickened ring. This gives the placenta a different appearance from a typical placenta.

A circumvallate placenta may be suspected during an ultrasound, but diagnosing it before delivery can be difficult because the ultrasound appearance does not always accurately match the final appearance of the placenta after birth. It is also important to remember that an ultrasound finding of a circumvallate placenta does not automatically mean that the baby will have health problems.

What Effects Does Circumvallate Placenta Have on Pregnancy?

Older studies have linked circumvallate placenta with complications such as bleeding, preterm birth, placental abruption and restricted fetal growth. However, more recent research suggests that a circumvallate placenta diagnosed during pregnancy may not always lead to these complications.

Some women may have an entirely normal pregnancy and deliver a healthy baby.

Depending on the individual situation, doctors may watch for:

A circumvallate placenta alone does not mean these complications will happen. Your doctor will assess your pregnancy based on the complete clinical picture.

Is Vaginal Delivery Possible if You Have Circumvallate Placenta?

Yes. Having a circumvallate placenta does not automatically mean that you need a C-section.

Many women can have a vaginal delivery if there are no other medical reasons for a caesarean birth. The decision about how and when to deliver depends on factors such as:

If another pregnancy complication develops, your doctor may recommend induction of labour or a C-section depending on the circumstances.

What Is the Difference Between Circumvallate Placenta and a Normal Placenta?

A normal placenta usually has a relatively smooth edge, with the fetal membranes extending from the placental margin. With a circumvallate placenta, the membranes attach farther inward from the placental edge. The tissue at the edge can fold back toward the fetal surface, creating a raised ridge or ring.

Structural Differences

Functional and Health Differences

The placenta normally provides oxygen and nutrients to the baby and removes waste products from the baby’s blood. A circumvallate placenta has an unusual structure, but this does not necessarily mean that the placenta will not function properly. Some pregnancies with this finding progress normally.

Earlier research has reported associations with fetal growth problems, preterm birth and placental bleeding. However, a recent study of pregnancies diagnosed with circumvallate placenta on prenatal ultrasound found no significant difference in adverse pregnancy outcomes compared with pregnancies without this ultrasound finding.

What Are the Causes of Circumvallate Placenta?

The exact reason why a circumvallate placenta develops is not known. It is thought to be related to how the placenta and its membranes develop and attach to the uterus during early pregnancy. 

There is currently no good evidence that a mother’s everyday activities, diet or routine behaviour causes a circumvallate placenta. In most cases, there is nothing a woman could have done to prevent it.

What Are the Symptoms of Circumvallate Placenta?

A circumvallate placenta usually does not cause specific symptoms on its own. Some women may experience vaginal bleeding during pregnancy, but bleeding can have many different causes and does not necessarily mean that the placenta is circumvallate. Symptoms such as bleeding, abdominal pain or contractions should always be discussed with a healthcare professional because they may require evaluation. 

If you experience heavy vaginal bleeding, severe abdominal pain, regular painful contractions, leaking fluid or reduced fetal movement later in pregnancy, seek medical attention promptly.

Pregnancy Complications with Circumvallate Placenta

A circumvallate placenta has been associated in some studies with pregnancy complications such as:

However, these complications do not occur in every pregnancy with a circumvallate placenta. A prenatal ultrasound diagnosis by itself may not predict a poor pregnancy outcome.

How to Diagnose Circumvallate Placenta?

A doctor may suspect a circumvallate placenta during a routine pregnancy ultrasound.

How to Manage Circumvallate Placenta?

No specific treatment can change the shape of a circumvallate placenta during pregnancy. Management depends on your overall pregnancy rather than the placental appearance alone.

Your doctor may recommend:

Importantly, there is no strong evidence that every woman with a circumvallate placenta diagnosed on ultrasound needs extra monitoring solely because of this finding. Your doctor may recommend additional surveillance when there are other concerns, such as fetal growth problems or bleeding.

Circumvallate Placenta Survival Rate

No specific “survival rate” applies to all pregnancies with a circumvallate placenta. The outcome depends on several factors, including whether the diagnosis was confirmed, the baby’s growth, gestational age, the presence of bleeding or placental complications, and the mother’s overall health.

Most importantly, being told that you have a circumvallate placenta does not mean that you will lose the pregnancy or that your baby will have a poor outcome. Recent research on prenatal ultrasound diagnosis found generally reassuring pregnancy outcomes.

Conclusion

A circumvallate placenta is an uncommon variation in placental structure. Although earlier research has associated it with complications such as bleeding, preterm birth, fetal growth problems and placental abruption, newer evidence suggests that a prenatal ultrasound diagnosis does not necessarily predict an unhealthy pregnancy.

There is no specific treatment to correct the placenta's shape. Instead, your doctor will consider the full picture, including your symptoms, the baby’s growth, and other pregnancy findings.

If you have been diagnosed with a circumvallate placenta, try not to panic. Continue your prenatal appointments and follow your obstetrician’s advice. Contact your healthcare provider if you experience vaginal bleeding, severe abdominal pain, regular contractions, leaking fluid or reduced fetal movement.