Placenta accreta spectrum (PAS) disorder is a serious pregnancy condition in which the placenta grows too deeply into the wall of the uterus. It can lead to complications during childbirth, which may necessitate a C-section or hysterectomy.
Once thought to be rare, this condition is becoming more common. Placenta accreta occurs in one of every 272 pregnancies, according to the American College of Obstetricians and Gynecologists (ACOG). This increase is likely because more people are having C-section deliveries, and the placenta is more likely to grow deeply into existing scar tissue.
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Placenta accreta spectrum disorder (PAS) is when the placenta grows too deeply into the uterine wall. It is a serious pregnancy condition – placenta accreta can be life-threatening.
The placenta is the organ that supplies oxygen and food to your growing baby through the umbilical cord. During labor, the placenta separates from your uterus right after birth. When the placenta attaches too deep, it can't easily separate. This attachment can lead to heavy bleeding and other problems.
Thankfully, many cases of PAS are detected ahead of time using an ultrasound. If you have placenta accreta, you'll work closely with your health care team for a safe pregnancy and delivery. To stop the bleeding, your doctor may need to do a C-section or remove the uterus (a hysterectomy) after birth.
PAS encompasses three types of abnormal placental attachment:
Although placenta accreta is one type of PAS disorder, the term “placenta accreta” is often used to describe any of the three types of abnormal placental attachment.
One common cause of PAS is scarring from previous uterine surgery. This scar tissue is often from a previous C-section delivery. Because C-sections have become more common, so has PAS.
These factors increase your risk of placenta accreta:
Placenta accreta is very dangerous for moms-to-be. It may cause life-threatening bleeding when you're giving birth to your baby. It might also cause you to go into labor too early.
Complications that may arise due to placenta accreta spectrum disorder include:
PAS does not appear to affect a person’s fertility.
Placenta accreta is life-threatening. The birthing parent can bleed so heavily that they die. In an advanced medical system, it may be possible to get the rate of maternal death as low as 0.5%, according to a study in Best Practice & Research Clinical Obstetrics & Gynaecology.
However, maternal mortality from PAS depends mostly on finding it early and taking steps to avoid maternal bleeding. Historical estimates place the survival rate for expected PAS in lower-income countries around 93% — about 7% of people who are diagnosed with PAS before birth die during labor.
This number drops substantially – to a 70% survival rate — for unexpected PAS, people who don't know they have PAS before birth and labor.
Placenta accreta may not cause any symptoms during your pregnancy. But you might have vaginal bleeding in your third trimester.
Tell your doctor right away if you have any bleeding during your pregnancy, and go to the hospital immediately if it's severe.
It is best if your doctor finds PAS before you go into labor (antenatal). If your doctor finds PAS before birth, it is “expected PAS.” Knowing you have PAS ahead of time leads to the best outcomes, as the doctors can offer specialized care to prevent bleeding and address it if it happens.
When your doctor diagnoses PAS during delivery (intrapartum), it is “unexpected PAS.” Unexpected PAS is relatively common — risk factors like placenta previa and previous C-sections are not always present.
If your doctor thinks you're at risk for PAS, they can diagnose it with an ultrasound. Sometimes, they find it during a routine prenatal ultrasound, as well. An ultrasound is a painless test using sound waves to see your uterus.
Doctors can identify PAS on an ultrasound as early as the first trimester. However, it's most often diagnosed during the second or third trimester.
If you have placenta accreta, you'll see a maternal fetal medicine specialist. They will work with your ob-gyn to protect you and your baby during your high-risk pregnancy.
If you have PAS, your doctor will help you design a birth plan that's safe for you and your baby. There is no way to fix placenta accreta. Your doctor will help you make a plan to keep you and your baby as safe as possible.
They may suggest:
If you have PAS and you’re planning on getting pregnant again, it is crucial to talk to your doctor early to discuss treatments. A hysterectomy will leave you unable to get pregnant again, while a C-section will increase your risk of PAS in future pregnancies.
There isn't a way to prevent PAS. But you can significantly reduce your risk by only having a C-section if it's medically necessary; this will reduce scarring in your uterus.
Make sure you tell your ob-gyn about your surgical history. If the doctor thinks you're at risk, they can do an ultrasound early to check your placenta.
By UPMC Editorial Staff. Last reviewed on 2024-09-05.
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