Diagnosing Placenta Accreta in Pregnancy

Woman and her doctors at an ultrasound
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Placenta accreta is a life-threatening condition that develops in pregnancy when the placenta grows too deeply into your uterine wall making it unable to separate easily. Typically the placenta attaches to the uterus in a way that, after the baby is born, the uterus contracts and the placenta is released—usually within about a half an hour after the birth of the baby.

In the case of a placenta accreta, the placenta is not released by uterine contractions and can lead to excessive bleeding, hemorrhage, the loss of the uterus, and even maternal death.

If the placenta grows to involve the muscles of the uterus, it is called a placenta increta. If the placenta grows through the uterine wall, it is known as a placenta percreta.

Risk Factors 

You are most at risk of having a placenta accreta if you have had a previous cesarean delivery and the placenta implants over your scar. A regular ultrasound can be a very good tool for determining if you have abnormalities with your placenta. So if you have had a previous cesarean birth, you will want to ask your health provider about looking at the ultrasound for proof that your placenta is normally attached. 

The rate of placenta accreta has been rising, which parallels the rise of the cesarean rates too. In the 1970s, research shows a rate of 1 in 4,027 pregnancies experienced an accreta, which rose to about 1 in 2,510 pregnancies in 1982. However, if you look at data for 1982-2002, the rate of accreta was 1 in 533 pregnancies.

If you have a placenta previa, where the placenta implants near the lower part of the uterus, covering all or part of the cervix, the risk of a placenta accreta goes up with each previous cesarean delivery you have had. Researchers found that the risk of placenta accreta when you have placenta previa and one previous cesarean is three percent.

As the number of cesareans goes up, so does the risk for a placenta accreta.

After five or more cesarean births—if you have a placenta previa—you have a 67% chance of experiencing an accreta as well.

To put this in perspective, if you had a placenta previa with no previous uterine surgery, you would have a one to five percent risk of an accreta.

There are other risk factors that can increase your risk of having a placenta accreta, though the previous cesarean is the biggest. These include:

  • Advanced maternal age
  • Having more than one child
  • Previous myomectomy
  • Thermal ablation
  • Uterine artery embolization
  • Asherman syndrome

Delivery With Placenta Accreta

If you have a known case of placenta accreta, you will be advised to have a scheduled cesarean delivery. While the date chosen will balance your baby’s health with your health, this may be as early as 34 weeks gestation. This often means that treatment with steroids to help improve your baby’s lungs will be advised. And, even with a planned delivery, you should ask what to do if you think you’ve gone into labor early and what other symptoms to look out for. 

Your doctor will assemble a team to help during your surgery. This may also mean that you need to move to a hospital that is equipped to handle this type of surgical birth. The bigger, more well-equipped hospitals offer you the best chance for the healthiest outcome.

Because about 90% of mothers with placenta accreta require a blood transfusion, planning ahead and coordinating with the hospital staff and blood bank are important steps. Sometimes, you can ask your doctor about banking blood specifically for your use, if you are concerned.

Your doctor should also talk to you about the fact that you may lose your uterus in the process. Some studies show that the best outcomes include planning ahead to do a cesarean hysterectomy. This means that after the birth of the baby via cesarean section, the uterus is removed rather than risk trying to remove the placenta from the uterus and incur even more risk of bleeding and damage. This is a very serious condition. In fact, the risk of maternal mortality associated with this procedure is as high as seven percent.

The good news is that we have the technology to determine if you have a placenta accreta well before delivery. We also have the technology and surgical advances to help assist you during the birth. If you have been diagnosed with a placenta accreta, you may ask your doctor to help connect you with others who have had similar experiences. Talking about this can be very helpful and make you feel calmer about the process.

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