What Is Placenta Accreta?
During pregnancy, a woman’s placenta attaches itself to her uterine wall and detaches after childbirth. Placenta accreta is a serious pregnancy complication that can occur when the placenta attaches itself too deeply into the uterine wall.
This causes part or all of the placenta to stay firmly attached to the uterus during childbirth. Placenta accreta can result in severe bleeding after delivery.
According to the American Congress of Obstetricians and Gynecologists (ACOG), 1 in 533 American women experience placenta accreta each year. In some cases of placenta accreta, a woman’s placenta will attach so deeply into the uterine wall that it attaches to uterine muscle. This is called placenta increta. It can even go more deeply through the uterine wall and into another organ, such as the bladder. This is called placenta percreta.
Placenta accreta is considered a potentially life-threatening pregnancy complication. Sometimes placenta accreta is discovered during delivery. But in many cases, women are diagnosed during pregnancy. Doctors will usually perform an early cesarean delivery and then remove the woman’s uterus, if the complication is detected before delivery. Removal of the uterus is called a hysterectomy.
Women with placenta accreta usually don’t display any signs or symptoms during pregnancy. Sometimes a doctor will detect it during a routine ultrasound.
But in some cases, placenta accreta causes vaginal bleeding during the third trimester (weeks 27 to 40). Contact your doctor right away if you experience vaginal bleeding during your third trimester. If you experience severe bleeding, such as bleeding that soaks through a pad in less than 45 minutes, or that is heavy and accompanied by abdominal pain, you should call 911.
It’s not known exactly what causes placenta accreta. But doctors think it’s linked to existing irregularities in the uterine lining and high levels of alpha-fetoprotein, a protein produced by the baby that can be detected in the mother’s blood.
These irregularities can result from scarring after a cesarean delivery or uterine surgery. These scars allow the placenta to grow too deeply into the uterine wall. Pregnant women whose placenta partially or fully covers their cervix (placenta previa) are also at a higher risk of placenta accreta. But in some cases, placenta accreta occurs in women without a history of uterine surgery or placenta previa.
Having a cesarean delivery increases a woman’s risks of placenta accreta during future pregnancies. The more cesarean deliveries a woman has, the greater her risks. The American Pregnancy Association estimates that women who have had more than one cesarean delivery account for 60 percent of all placenta accreta cases.
Doctors sometimes diagnose placenta accreta during routine ultrasound tests. However, your doctor usually run several tests to ensure the placenta is not growing into the uterine wall if you have several risk factors for placenta accreta. Some common tests to check for placenta accreta include imaging tests, such as ultrasound or magnetic resonance imaging (MRI) and blood tests to check for high levels of alpha-fetoprotein.
Several factors are thought to increase a woman’s risk of developing placenta accreta. These include:
- past uterine surgery (or surgeries), such as a cesarean delivery or surgery to remove uterine fibroids
- placenta previa, a condition that causes the placenta to partially or fully cover the cervix
- a placenta located in the lower part of the uterus
- being over the age of 35
- past childbirth
- uterine abnormalities, such as scarring or uterine fibroids
Every case of placenta accreta is different. If your doctor has diagnosed placenta accreta, they will create a plan to make sure your baby is delivered as safely as possible.
Severe cases of placenta accreta are treated with surgery. First, doctors will perform a cesarean delivery to deliver your baby. Next, they may perform a hysterectomy, or remove your uterus. This is to prevent serious blood loss that can occur if part, or all, of the placenta is left attached to the uterus after your baby is delivered.
If you would like the ability to get pregnant again, there is a treatment option after your delivery that may preserve your fertility. It is a surgical procedure that leaves much of the placenta in the uterus. However, women who receive this treatment are at a higher risk of complications. Your doctor may recommend a hysterectomy if you continue to experience vaginal bleeding after the procedure. According to ACOG, it’s very difficult to get pregnant after this procedure.
Discuss all of your treatment options with your doctor. They will help you pick a treatment based on your individual circumstances.
Placenta accreta can cause serious complications. These include:
- severe vaginal bleeding, which may require a blood transfusion
- problems with blood clotting, or disseminated intravascular coagulopathy
- lung failure, or adult respiratory distress syndrome
- kidney failure
- premature birth
As with all surgeries, performing a cesarean delivery and hysterectomy to remove the placenta from the body can cause complications. Risks to the mother include:
- reactions to anesthesia
- blood clots
- wound infections
- increased bleeding
- surgical injury
- damage to other organs, such as the bladder, if the placenta has attached to them
Risks to the baby during a cesarean delivery are rare and include surgical injury or breathing problems.
Sometimes doctors will leave the placenta intact in your body, because it can dissolve over time. But doing so can cause serious complications. These may include:
- potentially life-threatening vaginal bleeding
- a blood clot blocking one or more arteries in the lungs, or pulmonary embolism
- the need for a future hysterectomy
- complications with future pregnancies, including miscarriage, premature birth, and placenta accreta
If placenta accreta is diagnosed and treated properly, women usually have a full recovery with no lasting complications.
A woman will no longer be able to conceive children if a hysterectomy is performed. You should discuss all future pregnancies with your doctor if your uterus was left intact after treatment. Research published in the journal Human Reproduction suggests that the rate of recurrence for placenta accreta is high in women who have had the condition before.