What Is Placenta Accreta?

a pregnant woman getting an ultrasound in a medical office

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What Is Placenta Accreta?

Placenta accreta is a life-threatening complication that develops in pregnancy when the placenta, the organ that sustains the baby in utero, grows too deeply into the uterine wall, making it unable to separate after delivery. The term placenta accreta spectrum (PAS), encompasses placenta accreta and several other related placental abnormalities. This condition is a leading cause of maternal mortality.

In fact, research suggests that up to 7% of women with this condition may die as a result of PAS, and up to 60% experience significant complications. However, these rates are reduced with expert medical care and discovery of the condition prior to childbirth.

In the case of a placenta accreta, the placenta is not released by uterine contractions and can lead to excessive bleeding (hemorrhage), the loss of the uterus, and even maternal death.

Two related complications of the placenta that are even more severe are placenta increta and placenta percreta. When the placenta grows into the muscles of the uterus, this is called a placenta increta. If the placenta grows through the uterine wall (and sometimes into neighboring organs like the bladder), this is known as a placenta percreta.

Placenta previa is a complication that increases the risk of placenta accreta. In placenta previa, the placenta grows over and/or adjacent to the cervix

Symptoms

Generally, there are no symptoms of placenta accreta until delivery. When placenta accreta develops along with placenta previa (the two conditions commonly occur together), bleeding is a frequent symptom, as placenta previa often causes painless, bright red vaginal bleeding beginning in the second trimester.

If the condition is not discovered before labor and vaginal childbirth occurs, symptoms during delivery will include heavy vaginal bleeding. Additionally, after vaginal delivery, the placenta, which is usually delivered about 30 minutes after the baby, does not detach from the uterine wall as it normally would.

Diagnosis

The good news is that there is technology that can determine if you have placenta accreta well before delivery. Ultrasound is the usual method of diagnosis of placenta accreta (and other placental abnormalities). Ideally, this condition is diagnosed prior to labor so that the accreta can be managed for successful childbirth. However, as many as half or more of all PAS cases remain undiagnosed until childbirth.

Your doctor will look for any abnormalities with your placenta when conducting routine exams. If you have had a previous cesarean birth or if you have placenta previa, your health provider may do even more thorough ultrasound testing to determine if the placenta is attached normally. If needed, magnetic resonance imaging (MRI) can also be used to diagnose this condition.

When placenta accreta is missed during pregnancy and discovered during childbirth, an emergency c-section and/or hysterectomy is often needed to deliver the baby and stop the bleeding caused by this condition.

Causes

Typically, the placenta attaches to the uterus such that, after the baby is born, the uterus contracts and the placenta is released. But with placenta accreta, this process is disrupted. You are most at risk of having a placenta accreta if you have had a previous cesarean delivery and the placenta implants over your scar, especially if you also have placenta previa.

Incidence Is Increasing

The rate of placenta accreta has been rising, which parallels the rise of cesarean section births. Researchers believe growing rates of c-section births may be responsible for this jump in cases of placenta accreta. In fact, in 2003, the c-section rate in the United States was 26%. By 2019, it was 32%, more than double the 15% target rate recommended by the World Health Organization.

Rates of PAS have also significantly jumped. In the 1970s, research shows a rate of 1 in 4,027 pregnancies experienced an accreta, which rose to about 1 in 2,510 pregnancies in 1982. Data for the period between 1982 to 2002 shows a significantly increased rate of 1 in 533 pregnancies. Alarmingly, a comprehensive 2016 study documented a rate of 1 in 272 pregnancies.

Placenta Previa

If you have placenta previa, where the placenta covers all or part of the cervical opening, the risk of a placenta accreta goes up precipitously, particularly with each previous cesarean delivery or other uterine surgery you have had.

For example, if you have a placenta previa after one cesarean birth, you have a 3% chance of experiencing an accreta as well. This rate skyrockets to 40% after three c-sections.

To put this in perspective, if you had a placenta previa with no previous uterine surgery (including c-section), you would have less than a 1% risk of an accreta.

Additional Risk Factors

There are other risk factors that can increase your risk of having a placenta accreta, though the previous cesarean is the largest. These include:

  • Advanced maternal age
  • Asherman syndrome
  • Having more than one child
  • In vitro fertilization or other fertility treatments
  • Previous myomectomy (surgery to remove uterine fibroids)
  • Thermal ablation (vaporization of cancer and tumor cells)
  • Uterine artery embolization (a radiology treatment for uterine fibroids)

Treatment

Placenta accreta is a very serious, potentially life-threatening complication that needs appropriate treatment. Luckily, we now have the technology and surgical advances to keep both you and your baby safe during delivery, which almost always includes a c-section birth.

Cesarean Section

If you are diagnosed with placenta accreta before delivery, you will be advised to have a scheduled cesarean delivery. While the date chosen will balance your baby’s health with your health, this is often as early as 34 to 36 weeks gestation.

This means that treatment with steroids may be needed to mature your baby’s lungs before a preterm delivery. Some preterm infants will need care in a neonatal intensive care unit (NICU).

Waiting to deliver past 36 weeks is not recommended for most known pregnancies with placenta accreta because of the increased risk for hemorrhage.

High-Risk Care

Once diagnosed, talk to your doctor about their expertise with PAS and whether or not they are the best person to manage your care. If they are not highly experienced in treating placenta accreta, they will likely refer you to a specialist who is. You can also decide to switch to a more experienced physician if you have any qualms about your current doctor's qualifications.

Additionally, you may need to reconfigure your birth plan, including where you deliver. Ideally, deliver at a tertiary care level hospital that is equipped to handle this type of complex surgical birth.

Bigger, well-equipped hospitals offer the best chance for the healthiest outcome, as they have more expertise, highly trained specialists, and access to top-of-the-line equipment, and they handle more of these cases.

It's imperative for the health and safety of your baby and yourself to seek prenatal and childbirth medical care from hospitals and doctors well-trained and well-equipped for treating placenta accreta, including blood transfusion support and multi-disciplinary teams of doctors to support your delivery.

Blood Transfusions

Sometimes, massive hemorrhages occur before, during, and/or after delivery requiring blood transfusions. In fact, over 90% of mothers with placenta accreta require a blood transfusion, so planning ahead and coordinating with the hospital staff and blood bank are important steps. Sometimes, you can ask your doctor about banking blood prior to delivery specifically for your use.

Hysterectomy

An often upsetting truth about treating PAS is that you may lose your uterus in the process of successfully managing your care. In fact, many studies show that the best outcomes include planning ahead to do a cesarean hysterectomy.

This means that after the birth of the baby via cesarean section, the uterus is removed rather than trying to remove the placenta from the uterus and risk incurring even more bleeding and damage.

In isolated cases, when the mother hopes to retain fertility, new procedures are emerging that may successfully save the uterus. However, this option is not recommended or possible for most women.

For many women with PAS, treatment will include c-section delivery and hysterectomy.

Coping

Women who experience placenta accreta may be more prone to postpartum depression and/or anxiety. Coping with a traumatic birth, hemorrhaging, and/or the loss of fertility while also caring for an infant is challenging emotionally and physically. Be patient and kind to yourself as you heal and adjust to life as a mother.

If you are struggling emotionally, it might be helpful to connect with others who have had similar experiences. Your doctor may be able to facilitate this or have ideas about local organizations that can assist you. Additionally, the National Accreta Foundation offers support groups and other resources about this complex condition.

Learning more about your condition and talking to others about any fears or concerns you have can be therapeutic and may help you feel more comfortable with the placenta accreta treatment and recovery process.

A Word From Verywell

Finding out that you have placenta accreta is scary. Thankfully, the condition can usually be safely managed through surgical interventions. Still, it's often a shock to discover you have PAS and upsetting to learn that you'll likely need to deliver your baby early via c-section—and possibly have a hysterectomy.

Focusing on the baby you'll soon meet can help put the high-stakes (and potential disappointments) of your delivery in perspective.

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