You may have never heard of placenta accreta, because it has been a rare condition. However, it is becoming a lot more common, especially in women who have had a C-section. According to the American College of Obstetricians and Gynecologists (ACOG), the frequency of placenta accreta was about one in 2,500 pregnancies back in the 1980s. As the frequency of C-sections has increased, so has placenta accreta. It may be occurring in about one in 500 pregnancies now.
What is placenta accreta?
Placenta accreta describes a condition in which your placenta grows too deeply into the wall of your uterus. The word accreta means increased growth. This condition is sometimes called accreta spectrum because there are different degrees of growth.
Placenta accreta is the most common type, the placenta grows into the deep tissues of the uterus. Placenta increta is growth into the muscle of the uterus, and placenta percreta grows completely through the wall of the uterus. Most doctors use the term placenta accreta to include all the types.
The danger from placenta accreta is very severe bleeding. Instead of the placenta coming out in afterbirth, it adheres tightly the uterus. Trying to remove it can cause life-threatening hemorrhage that almost always results in an emergency hysterectomy.
Who is at risk?
According to ACOG, the main cause of placenta accreta is scar tissue in the uterus, and the main cause of scar tissue is a previous C-section. The frequency of this condition is about half of one percent after one C-section but increases with each succeeding C-section. For women who have had five or more C-sections, the frequency is almost seven percent. Sixty percent of women with placenta accreta have had multiple C-sections, says ACOG.
Another contributing factor is placenta previa, that is when the placenta implants low in the uterus over the area of the cervix. Women who have both placenta previa and a history of C-sections are at highest risk for this condition. For example, a woman with placenta previa who has had three C-sections, will have almost 50 percent chance of placenta accreta. Other risk factors are a history smoking and being pregnant at age 35 or older.
How is this condition diagnosed and treated?
Fortunately, this condition is usually diagnosed early in pregnancy. A prenatal ultrasound can diagnose placenta accreta as early as the first trimester. Sometimes an MRI imaging study is done to confirm the diagnosis. Once the condition is diagnosed, the pregnancy is considered high-risk and delivery should be planned at a hospital equipped for high-risk deliveries and experienced in treating the condition. This is called level III obstetric centers.
Treatment is almost always a cesarean hysterectomy. This is the safest way to deliver the baby for both the mother and the baby. A C-section is planned for 34 to 38 weeks of pregnancy. The baby is safely delivered by C-section. Because tying to separate the placenta from the uterus can cause life-threatening bleeding, the uterus is removed after the C-section. It is the safest treatment, but future pregnancies are no longer possible.
Can placenta accreta be prevented?
The best way to prevent this condition is to only have a C-section if you really need one. According to the Harvard School of Public Health, about 90 percent of women who have one C-section will need a C-section for any future pregnancies. With each C-section your risk of placenta accreta and cesarean hysterectomy go up. If you have had one or two C-sections, you should talk to your doctor about the risk of future pregnancies.