Placenta Accreta: Symptoms, Causes, and Risks

In most pregnancies, the placenta easily detaches from the wall of the uterus after delivery, but in some rare cases the placenta grows too deeply into the wall of the uterus and becomes inseparable. This serious pregnancy complication is called placenta accreta. Read on to learn about the causes, symptoms, and risk factors of this condition, and what your healthcare provider may do if you are diagnosed with placenta accreta.

What Is Placenta Accreta?

The placenta is an organ that forms in your uterus during pregnancy to supply oxygen and nutrients to your baby. As it grows, the placenta attaches to the uterus wall. In some rare cases (in about 1 in every 533 pregnancies) the placenta grows too deeply into the uterine wall and can’t easily separate away after your baby is born. This condition is what’s called placenta accreta.


Placenta accreta and normal placenta

What Can Happen If You Have Placenta Accreta?

Placenta accreta is a serious condition that could lead to life-threatening amounts of vaginal bleeding (hemorrhage) after you give birth. This can happen if part of the placenta remains attached to the uterine wall, while the rest tears away during delivery.

The heavy vaginal bleeding associated with placenta accreta can prevent the blood from clotting as it normally would, and can also lead to lung and kidney failure.

Placenta accreta increases the risk of premature labor.

If the condition causes you to start bleeding during your pregnancy, you might be required to deliver your baby early via cesarean section.

If your healthcare provider diagnoses placenta accreta, you will have lots of questions about what might happen. Your provider will answer all of your questions, and make a plan to ensure you and your baby are kept safe, and lower the risk of complications.

Types of Placenta Accreta

Placenta accreta is the general term to describe this condition, but there are three specific types of this condition:

  • Placenta accreta. The placenta firmly attaches to the wall of the uterus, but does not pass through the wall or impact the muscular wall of the uterus.
  • Placenta increta. The placenta is more deeply embedded in the wall of the uterus and also firmly attaches to the muscular wall of the uterus.
  • Placenta percreta. The placenta extends through the wall of the uterus and muscles and, in some cases, attaches to other nearby organs such as the bladder or intestines.

What Causes Placenta Accreta?

It's not clear what triggers placenta accreta. In some cases, it is thought to be related to abnormalities in the lining of the uterus, which are often due to scarring after a cesarean section or another uterine surgery. Keep in mind, this condition can happen even if you haven't had any kind of uterine surgery before.

Symptoms of Placenta Accreta

There are often no signs or symptoms of placenta accreta during pregnancy. In some cases, though, bright red vaginal bleeding without pain during the third trimester or a little earlier could be a sign.

This type of bleeding may also be a sign of placenta previa, which is when the placenta lies low in the uterus and covers all or part of the cervix. Speak to your healthcare provider right away if you notice any vaginal bleeding during your pregnancy.

Risk Factors for Placenta Accreta

Although it's not always known what causes placenta accreta, risk factors include:

  • Uterine surgery. Any kind of surgery on the uterus that has caused damage to the myometrium, which is the muscle wall of the uterus, increases the risk of placenta accreta. Surgeries that cause scarring to the uterus include a cesarean section, the surgical removal of fibroids that are inside the uterus wall, uterine artery embolization, and endometrial ablation.
  • One or more previous pregnancies. The risk for placenta accreta increases with each pregnancy.
  • Being more than 35 years old.
  • The position of the placenta. If you have placenta previa, your risk of placenta accreta increases.


In the past, placenta accreta often wasn't diagnosed until after the baby was delivered. In some cases, this can still happen, but it's now most often diagnosed during pregnancy with an ultrasound scan.

This is good news, because an early diagnosis means your healthcare provider can try to prevent or better prepare for complications, such as heavy bleeding.

If you have any of the risk factors, your healthcare provider will more carefully watch for placenta accreta. If the results of the ultrasound aren't clear, you may have magnetic resonance imaging (MRI) done.

If you are diagnosed with placenta accreta, your healthcare provider will give you guidance about how you and your baby will be kept safe throughout your pregnancy and delivery.

Treatment for Placenta Accreta

Placenta accreta can't be cured during pregnancy; however, the risks associated with it can be managed.

If placenta accreta is diagnosed early, treatment typically involves a planned cesarean section to deliver your baby, followed by a hysterectomy. A hysterectomy is when all or part of the uterus is removed. In some cases, it may be possible to avoid having a hysterectomy. Your healthcare provider will discuss all of your options with you.

Depending on what your healthcare provider thinks is the safest, the cesarean section may be scheduled early, or it may not be performed until your pregnancy is full term. In some cases, an emergency cesarean section may be needed if unexpected issues arise.

Your healthcare provider may offer or recommend an amniocentesis test. This test can help your provider determine the best timing for the cesarean, as it can help assess whether your little one's lungs are mature enough for birth.

In some cases, you may be given corticosteroids to speed up the development of your baby's lungs and other organs. This helps protect your baby should your provider think an early cesarean delivery is safest.


  • What causes placenta accreta?

Placenta accreta is thought to be caused by abnormalities or scarring in the uterus wall, though in some cases it’s not clear what the cause is.

  • How common is placenta accreta?

In 2015, the rate of placenta accreta was about 1 in 533 pregnancies. Experts say the rising rate of cesarean sections might cause this number to increase. This is because placenta accreta is related to abnormalities in the lining of the uterus that are often due to scarring after a cesarean section or another uterine surgery.

Placenta accreta is a serious condition, but an early diagnosis can help lower the risks of any complications, and help ensure that you and your baby are kept as safe as possible.

Healthy pregnancyPregnancy conditions

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