Placenta accreta is a serious pregnancy condition that occurs when the placenta grows too deeply into the uterine wall.
Typically, the placenta detaches from the uterine wall after childbirth. With placenta accreta, part or all of the placenta remains attached. This can cause severe blood loss after delivery.
It's also possible for the placenta to invade the muscles of the uterus (placenta increta) or grow through the uterine wall (placenta percreta).
Placenta accreta is considered a high-risk pregnancy complication. If the condition is diagnosed during pregnancy, you'll likely need an early C-section delivery followed by the surgical removal of your uterus (hysterectomy).
Placenta accreta often causes no signs or symptoms during pregnancy — although vaginal bleeding during the third trimester might occur.
Occasionally, placenta accreta is detected during a routine ultrasound.
Placenta accreta is thought to be related to abnormalities in the lining of the uterus, typically due to scarring after a C-section or other uterine surgery. Sometimes, however, placenta accreta occurs without a history of uterine surgery.
Many factors can increase the risk of placenta accreta, including:
- Previous uterine surgery. The risk of placenta accreta increases with the number of C-sections or other uterine surgeries you've had.
- Placenta position. If the placenta partially or totally covers your cervix (placenta previa) or sits in the lower portion of your uterus, you're at increased risk of placenta accreta.
- Maternal age. Placenta accreta is more common in women older than 35.
- Previous childbirth. The risk of placenta accreta increases as your number of pregnancies increases.
Placenta accreta can cause:
- Heavy vaginal bleeding. Placenta accreta poses a major risk of severe vaginal bleeding (hemorrhage) after delivery. The bleeding can cause a life-threatening condition that prevents your blood from clotting normally (disseminated intravascular coagulopathy), as well as lung failure (adult respiratory distress syndrome) and kidney failure. A blood transfusion will likely be necessary.
- Premature birth. Placenta accreta might cause labor to begin early. If placenta accreta causes bleeding during your pregnancy, you might need to deliver your baby early.