Learning About Placenta Accreta Spectrum

Placenta accreta spectrum (PAS) is a condition that happens during pregnancy when the placenta grows too deeply into the wall of the uterus.

The placenta gives oxygen and nutrients to the baby. It also removes waste products. Normally the placenta attaches to the lining of the uterus and separates after the baby is born.

With PAS, part or all of the placenta is attached too firmly. This can make it hard or impossible for the placenta to separate after delivery. PAS can cause severe bleeding and other serious problems.

PAS includes three types:

• Placenta accreta. The placenta grows too deeply into the wall of the uterus but does not grow into the muscle.
• Placenta increta. The placenta grows into the muscle of the uterus.
• Placenta percreta. The placenta grows through the wall of the uterus. It may attach to nearby organs, such as the bladder.

The cause isn't known. Certain things can increase the risk. These include:

• Prior cesarean delivery (C-section).
• Placenta previa. This is a condition in which the placenta covers part or all of the cervix.
• Prior surgery on the uterus, such as fibroid removal.
• Having had a dilation and curettage (D&C) procedure.
• Having had PAS before.
• Being over age 35.

The risk is highest if you've had placenta previa after a C-section.

There often aren't symptoms with PAS. It's often found during an ultrasound exam.

Symptoms can include:

• Vaginal bleeding during the second or third trimester.
• Bleeding without pain.

PAS is often found before delivery. Finding it early helps doctors plan a safer delivery.

Tests that find it may include:

• Ultrasound. This is the most common test used to find PAS.
• Magnetic resonance imaging (MRI). This test may be done in some cases, such as if the placenta is attached to nearby organs.

With early diagnosis and care, you can have a good outcome with PAS. But it can lead to serious problems. These include:

• Severe bleeding (hemorrhage).
• Need for blood transfusions.
• Injury to nearby organs, such as the bladder.
• Infection.
• Premature birth.
• Need for intensive care after delivery.

Treatment depends on how deeply the placenta has grown and if there are problems.

You may need:

• Care from a high-risk-pregnancy team.
• Delivery in a hospital that can perform complex surgery.
• A planned cesarean delivery.

In many cases, doctors suggest removing the uterus (hysterectomy) right after the baby is delivered. This helps prevent severe bleeding that can occur if doctors try to remove the placenta.