Abnormally Invasive Placenta


What is Abnormally Invasive Placenta?

During pregnancy, an organ called the placenta forms on the wall of the uterus and attaches to the superficial uterine lining. The placenta passes blood from the mother to the baby, giving the baby oxygen and nutrients until birth. Normally, the placenta separates from the uterus and is expelled when the baby is delivered. However, in some cases, the placenta grows too deeply into the muscles of the uterus and does not separate during birth. This is known as abnormally invasive placenta, also called morbidly adherent placenta.

Abnormally Invasive Placenta Risk Factors

Women who have had some type of damage to the lining of the uterus may have an increased risk of abnormally invasive placenta. The main risk factors for developing abnormally invasive placenta include:

  • Previous Caesarean section: Caesarean section procedures typically leave a scar on the wall of the uterus, which may increase the risk of an invasive placenta. Still, the majority of women who have had a Caesarean section do not develop abnormally invasive placenta in later pregnancies.
  • Previous uterine surgery: Women who have had uterine surgery such as fibroid surgery or have had one or more dilation and curettage (D&C) procedures, often done for bleeding problems, may have an increased risk.
  • Fibroid embolization treatment: This specific type of embolization treatment can raise the risk of invasive placenta.

Types of Abnormally Invasive Placenta

There are three types of abnormally invasive placenta ranging from mild to severe, depending on how far the placenta grows into the uterine lining:

  • Placenta accreta - the placenta grows through the superficial lining of the uterus and attaches to the uterine muscular layer.
  • Placenta increta - the placenta grows at least halfway into the muscular wall of the uterus
  • Placenta percreta - in rare cases, the placenta grows through the wall of the uterus and may grow into the bladder or other nearby organs.

Abnormally invasive placenta has no symptoms, so it may not be diagnosed until the baby is born and the placenta does not detach as expected. 

Diagnostic & Treatment Options

Diagnosing Abnormally Invasive Placenta

Prenatal ultrasound testing may detect the condition if the border or texture of the placenta appears to be abnormal. If the obstetrician suspects abnormally invasive placenta, they may order an MRI scan to try to confirm the diagnosis. Even so, it may still be difficult to know for sure until the baby is born.

Treating Abnormally Invasive Placenta

Mercy’s maternal and fetal medicine specialists develop personalized treatment plans for every woman with this challenging condition.

  • If diagnostic testing suggests that a woman has an abnormally invasive placenta, we may deliver the baby by Caesarean section.
  • If the placenta has not grown deeply into the uterine wall and the risk of excess bleeding is low, our surgeons may carefully remove the placenta.
  • If necessary, we may perform a hysterectomy at the same time to remove the entire uterus.
  • In severe cases, our expert team may need to perform more extensive surgery to repair the bladder or other organs involved, but this is unusual.

Most women with abnormally invasive placenta fully recover with no lasting problems, and the baby’s health is usually not affected at all. Your Mercy care team is here to help you and your baby have a safe and healthy delivery.

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