Pregnancy is usually a time of joy and anticipation, but it can also come with unexpected challenges. One of the rare but serious complications doctors watch closely for is Placenta Accreta Spectrum (PAS). This condition occurs when the placenta attaches too deeply into the wall of the uterus and doesn’t detach properly after delivery.
While PAS is uncommon, it can lead to dangerous bleeding if not carefully managed. Because of this, early detection and specialized care for PAS are key to protecting both mothers and babies.
What Is Placenta Accreta Spectrum?
The placenta is the lifeline between a birthing parent and their baby, as it delivers oxygen and nutrients to the developing baby during pregnancy.
Normally, the placenta attaches to the uterine wall and detaches on its own after birth. But in Placenta Accreta Spectrum (PAS), the placenta attaches too deeply into the wall of the uterus and does not separate properly after delivery.
PAS is considered a serious but rare pregnancy complication because it can lead to life-threatening bleeding if not properly managed.
Doctors call it a “spectrum” because there are different degrees of severity of PAS:
- Placenta accreta: The placenta attaches too deeply into the uterine lining (most common).
- Placenta increta: The placenta grows into the muscular wall of the uterus.
- Placenta percreta: The placenta grows through the uterine wall and may affect nearby organs like the bladder or colon.
Placenta Accreta Spectrum Risk Factors and Causes
PAS has become more common in recent decades, largely due to the rise in cesarean deliveries. The condition has increased from about 1 in 1,250 births in the 1980s to about 1 in 272 births today.
Pregnant people are at greater risk for PAS if they:
- Have had one or more cesarean deliveries (the risk rises with each surgery)
- Have placenta previa (when the placenta covers the cervix)
- Have had other uterine surgeries, such as myomectomy, dilation or curettage
- Are over age 35
- Have had multiple prior pregnancies and deliveries
For example, for women with placenta previa, the risk of placenta accreta is 3 percent, 11 percent, 40 percent, 61 percent and 67 percent, for the first, second, third, fourth and fifth or more cesarean, respectively.
Signs and Symptoms of PAS
One of the reasons PAS can be so dangerous is that it often develops without obvious warning signs during pregnancy. In fact, many pregnant people do not experience any PAS symptoms at all.
In many cases, this condition is detected through imaging (such as an ultrasound) in patients with known risk factors, rather than because of obvious symptoms.
That said, there are a few possible Placenta Accreta Spectrum symptoms to be aware of. For instance, when pregnant people do notice symptoms, it’s often bleeding during the second half of pregnancy.
Placenta Accreta Spectrum symptoms to watch for can include:
- Vaginal bleeding in the second or third trimester: This is the most common symptom that may point to placenta-related complications, including PAS. While not every case of bleeding is due to PAS, it’s important to have it evaluated promptly.
- Abnormal findings during ultrasound: PAS may first be suspected when the placenta appears unusually thick or invasive on routine scans. This is particularly true in patients with a history of cesarean births or placenta previa.
- Signs at delivery: In some cases, PAS is not discovered until childbirth, when the placenta does not detach as expected and significant bleeding occurs.
When to Call Your Doctor
Because PAS often doesn’t cause clear signs during pregnancy, risk factors and careful screening play a much larger role in diagnosis than symptoms alone.
If you’re pregnant and notice any unusual symptoms, such as bleeding or early contractions, it’s always safest to reach out to your doctor.
Seek medical attention right away if you experience:
- Heavy vaginal bleeding in the second or third trimester
- Severe abdominal or pelvic pain that doesn’t go away
- Contractions before 37 weeks
- Sudden dizziness, fainting or weakness
These signs don’t always mean you have Placenta Accreta Spectrum, but they may point to a complication that requires urgent care. The sooner you’re evaluated and receive help, the better your doctor will be able to help protect both you and your baby.
How PAS Is Diagnosed
Doctors often identify PAS during a routine ultrasound if risk factors are present. If PAS is suspected, a specialized ultrasound or MRI can be used to determine how deeply the placenta has grown into the uterine wall or surrounding organs.
Once diagnosed, PAS pregnancies are considered high-risk. They’re typically managed by a Maternal-Fetal Medicine team that specializes in treating PAS and similar conditions.
Treatment Options
Because PAS can cause severe bleeding, treatment usually involves a carefully planned delivery. This type of delivery and treatment plan for PAS can include:
- Scheduled cesarean delivery: Often performed before labor begins to reduce complications.
- Hysterectomy (removal of the uterus after delivery): Sometimes necessary if the placenta cannot safely be removed.
- Blood transfusions and advanced surgical support: May be required in cases of severe bleeding.
- Multidisciplinary care: Involves obstetricians, maternal-fetal medicine specialists, anesthesiologists, and surgical teams to ensure the safest possible outcome for both mother and baby.
The exact treatment depends on the severity of the condition, the mother’s health, and whether other organs are involved.
At Stony Brook Medicine’s Center for Placenta Accreta Spectrum, a part of the University Associates in Obstetrics & Gynecology, our specialists provide advanced, coordinated care for women with PAS and other complex placental conditions, such as placenta previa and placental abruption. With a team-based approach and access to state-of-the-art imaging and surgical techniques, we are equipped to manage high-risk pregnancies and help ensure the best possible outcomes for mothers and babies. Learn more here, or call (631) 444-4686 to make an appointment.
