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Placenta Accreta

by Julie S. Moldenhauer, MD

Placenta accreta is a placenta with an abnormally firm attachment to the uterus.

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.

This complication is more likely to occur in women

  • Who have had a cesarean delivery

  • Whose placenta covers the cervix

  • Who are over 35

  • Who have been pregnant several times

  • Who have fibroids under the lining of the uterus (endometrium)

  • Who have had surgery involving the uterus, including removal of fibroids

  • Who have disorders of the lining of the uterus, such as Asherman syndrome

Having a cesarean delivery greatly increases the risk of placenta accreta. The more cesarean deliveries a woman has had, the higher the risk.

Diagnosis

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, magnetic resonance imaging (MRI) may be done.

During delivery, the disorder is suspected if the placenta has not been delivered within 30 minutes after the baby’s delivery, if doctors cannot separate the placenta from the uterus by hand, or if attempting to remove the placenta results in profuse bleeding.

Treatment

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 done as soon as the fetus is mature enough, usually at about 35 to 36 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 or blood clots, which can travel through the bloodstream and block an artery in the lungs. A cesarean hysterectomy should be done at a hospital that is equipped to handle such complications.

If future childbearing is important to the woman and bleeding is unlikely to be profuse (because of the placenta's location), doctors try to preserve the uterus using various techniques.