Placenta Accreta
When the placenta attaches too deeply to the uterus
Quick Facts
- Type: Pregnancy (placental) condition
- Main risk: Severe bleeding at delivery
- Key risk factor: Prior cesarean or uterine surgery
- Usual delivery: Planned cesarean, often with specialists
Overview
Placenta accreta is a pregnancy condition in which the placenta, the organ that nourishes the baby, attaches too firmly and too deeply into the wall of the uterus. Normally the placenta separates and is delivered easily after the baby is born. With placenta accreta, it does not detach properly, which can lead to dangerous bleeding.
Doctors describe a range of severity known as the placenta accreta spectrum. In the mildest form the placenta is abnormally attached to the uterine wall; in more severe forms it grows into the muscle or even through the uterus to nearby organs. Because of the risk of heavy bleeding, placenta accreta is usually managed with careful planning, a scheduled cesarean delivery, and a team experienced in handling the condition.
Symptoms
Placenta accreta often causes no symptoms during pregnancy and is found on a routine ultrasound. When symptoms do occur, they can include:
- Vaginal bleeding during the third trimester, especially if placenta previa is also present
- No outward signs in many cases until delivery
The most serious problem usually appears at birth, when the placenta will not separate and heavy bleeding (hemorrhage) can occur. Any significant vaginal bleeding during pregnancy should be evaluated promptly, as it can signal a placental problem that needs urgent attention.
Causes
Placenta accreta is thought to happen when the lining of the uterus has been scarred or damaged, allowing the placenta to grow more deeply than normal. Contributing factors include:
- Previous cesarean deliveries, with risk rising as the number of cesareans increases.
- Placenta previa, where the placenta covers the cervix, especially over a prior cesarean scar.
- Prior uterine surgery such as fibroid removal or procedures that scar the lining.
- Other uterine conditions or scarring from past procedures.
The damaged area heals with scar tissue, which lacks the normal layer that keeps the placenta from invading too deeply.
Risk Factors
- One or more previous cesarean deliveries
- Placenta previa in the current pregnancy
- Prior surgery on the uterus
- Older maternal age
- Multiple past pregnancies
- Previous placenta accreta
Diagnosis
Placenta accreta is often suspected before birth, allowing time to plan safe delivery:
- Ultrasound: the main tool, which can show signs of abnormally deep placental attachment, especially in women with risk factors.
- MRI: sometimes used to clarify how deeply the placenta has grown or whether it involves nearby organs.
- Risk review: careful attention in women with prior cesareans or placenta previa, who are screened more closely.
Identifying it early lets the care team prepare for the safest possible delivery.
Treatment
Care focuses on protecting the mother from severe bleeding and is best done at a hospital with specialized teams. Management usually includes:
- Planned cesarean delivery: often scheduled before labor begins to reduce emergency bleeding.
- Hysterectomy: in many cases the uterus is removed at the same time, because leaving the deeply attached placenta in place can cause life-threatening bleeding.
- Blood transfusion readiness: the team prepares for possible heavy blood loss.
- Specialist team: care often involves maternal-fetal medicine, surgery, anesthesia, and blood bank support.
In selected cases, doctors may consider approaches that aim to preserve the uterus, but these require careful counseling about the risks.
Prevention
- Discuss the risks of repeat cesarean deliveries with your provider when planning pregnancies
- Attend all prenatal appointments and recommended ultrasounds
- Report any vaginal bleeding during pregnancy right away
- Make sure prior uterine surgeries are noted in your prenatal records
- Plan delivery at a hospital equipped to manage high-risk pregnancies if accreta is suspected
When to See a Doctor
Contact your provider promptly about any vaginal bleeding during pregnancy. Seek emergency care right away if you have:
- Heavy vaginal bleeding
- Severe abdominal or pelvic pain
- Feeling faint, dizzy, or short of breath
- A rapid heartbeat or signs of shock
Heavy bleeding in pregnancy or after delivery is an emergency. If placenta accreta has been diagnosed, follow your care team's delivery plan closely.
Frequently Asked Questions
What causes placenta accreta?
It usually develops where the uterine lining has been scarred, most often from previous cesarean deliveries or other uterine surgery. The scar tissue lets the placenta attach more deeply than normal, so it does not separate after birth.
Is placenta accreta dangerous?
Yes. The main danger is severe bleeding when the placenta will not detach during delivery. With early diagnosis and a planned cesarean at a hospital prepared for it, the risks can be managed much more safely.
Will I need a hysterectomy with placenta accreta?
Many women with placenta accreta have the uterus removed during the cesarean, because leaving the deeply attached placenta can cause life-threatening bleeding. In selected cases, uterus-sparing approaches may be considered after detailed counseling.
How is placenta accreta detected before birth?
It is often suspected on a prenatal ultrasound, especially in women with prior cesareans or placenta previa. An MRI is sometimes used to see how deeply the placenta has grown so the delivery can be planned safely.
References
- American College of Obstetricians and Gynecologists (ACOG). Placenta accreta spectrum.
- Mayo Clinic. Placenta accreta.
- MedlinePlus, U.S. National Library of Medicine. Placenta problems.
- National Institutes of Health (NIH). Placenta accreta spectrum.