Placenta accreta is a placenta with an abnormally firm attachment to the uterus.
Having had a cesarean delivery, having placenta previa (when the placenta covers the cervix) in the current pregnancy, or both increases the risk of placenta accreta.
If a woman has risk factors for placenta accreta, doctors do ultrasonography periodically during the pregnancy to check for this complication.
If the risk of placenta accreta is high, doctors may talk with a pregnant woman about planning a cesarean delivery with a hysterectomy (removing the uterus) a few weeks before the due date.
After delivery of the baby, the placenta usually detaches from the uterus, and a woman can push the placenta out by herself or with help from a doctor or midwife. When the placenta is too firmly attached, parts of the placenta may remain in the uterus after delivery. In these cases, delivery of the placenta is delayed, and the risks of bleeding and infection in the uterus are increased. Bleeding may be life threatening.
In the United States, rates of cesarean delivery have increased, and therefore rates of placenta accreta has also been increasing.
Risk factors
Having had a cesarean delivery in a previous pregnancy or having placenta previa in the current pregnancy increases the risk of placenta accreta. If both of these factors are present, the risk is greatly increased. Other risk factors include
Age 35 years or older
Multiple prior pregnancies
Fibroids under the lining of the uterus (endometrium)
Prior uterine surgery other than cesarean, including removal of fibroids
Disorders of the lining of the uterus, such as Asherman syndrome (scarring of the uterine lining due to an infection or surgery)
Diagnosis of Placenta Accreta
Ultrasonography
Sometimes magnetic resonance imaging (MRI)
If a woman has conditions that increase the risk of placenta accreta, doctors usually do ultrasonography before delivery to check for placenta accreta. Ultrasonography, using a handheld device placed on the abdomen or inside the vagina, may be done periodically, starting at about 20 to 24 weeks of pregnancy. If ultrasonography is unclear, MRI may be done.
During delivery, placenta accreta is suspected if any of the following occur:
The placenta has not been delivered within 30 minutes after the baby’s delivery.
Doctors cannot separate the placenta from the uterus by hand.
Attempting to remove the placenta results in profuse bleeding.
Treatment of Placenta Accreta
Cesarean hysterectomy
If doctors detect placenta accreta before delivery, a cesarean delivery followed by removal of the uterus (cesarean hysterectomy) is typically done. For this procedure, the baby is first delivered by cesarean. Then the uterus is removed with the placenta in place. This procedure is usually done at about 34 weeks of pregnancy. It helps prevent potentially life-threatening loss of blood, which can occur when the placenta remains attached after delivery. However, the procedure can cause complications, such as profuse bleeding. Also, blood clots can develop if the surgery takes a long time and/or requires a long period of bed rest afterward. Blood clots can travel through the bloodstream and block an artery in the lungs (a condition called pulmonary embolism). A cesarean hysterectomy should be done by an experienced surgeon and at a hospital that is equipped to handle the complications.
If future childbearing is important to a woman, doctors try to preserve the uterus using various techniques. However, these techniques cannot be used if bleeding is extremely heavy or is likely to be extremely heavy (because of the placenta's location).
