Disorder Types

Types of Placental Disorders

BIDMC's Placental Disorders Team The placenta is a structure that develops inside the uterus during pregnancy and provides oxygen and nutrition to the baby and eliminates waste products. The placenta connects to the baby through the umbilical cord. Normally, the placenta attaches at the top or side of the uterus. In some cases, the placenta develops in the wrong location or attaches itself too deeply into the uterine wall. These placental disorders are called placenta previa, placenta accreta, placenta increta or placenta percreta.

Placental disorders are usually diagnosed by ultrasound in the second trimester (about 18 to 20 weeks into a pregnancy).

Placenta Previa

Placenta previa occurs when the placenta covers some or all of the cervix. If you have placenta previa early in pregnancy, it usually isn't a problem. However, it can cause serious bleeding and other complications later in pregnancy.

Symptoms:
Placenta previa might cause bleeding throughout pregnancy and during delivery.

Diagnosis:
Placenta previa is usually discovered after a woman experiences bright red vaginal bleeding (without pain) during the second half of pregnancy. Some women also have contractions. Your obstetrics team will arrange for an ultrasound to confirm the diagnosis.

Treatment:
To limit bleeding during pregnancy, your obstetrics team will probably recommend avoiding activities that might cause contractions, including having sex, douching, using tampons, or engaging in activities that can increase your risk of bleeding, such as running, squatting, and jumping.

In many women diagnosed with placenta previa early in their pregnancies, the placenta previa resolves itself. As the uterus grows, it might increase the distance between the cervix and the placenta. The more the placenta covers the cervix and the later in the pregnancy that it remains over the cervix, the less likely it is to resolve. If the placenta previa doesn't resolve, the baby will be delivered by cesarean birth, usually around 37 weeks.

Placenta Accreta, Increta and Percreta

When the placenta attaches itself too deeply into the uterine wall, that is called placenta accreta, increta or percreta, depending on the severity and deepness of the placenta attachment. The risks include bleeding and subsequent complications. The baby will need to be delivered by cesarean weeks before the due date. And because the placenta will have difficulty separating from the uterine wall, hysterectomy (removal of the uterus) is often necessary.

Placenta Accreta

Placenta accreta occurs when the placenta attaches too deep in the uterine wall but it does not penetrate the uterine muscle.

The most severe complications occur during childbirth. In pregnancies without placental abnormalities, the placenta typically detaches from the uterine wall immediately after birth. With placenta accreta, part or all of the placenta remains attached, which can cause severe blood loss after delivery. If the condition is diagnosed during pregnancy, patients will likely need an early cesarean delivery followed by hysterectomy. Placenta accreta is the most common of the three placental disorders, accounting for approximately 75% of all cases.

The specific cause of placenta accreta is unknown, but it is often associated with a placenta previa and previous cesarean deliveries. A cesarean delivery increases the possibility of a future placenta accreta, and the more cesareans, the greater the increase. A history of multiple prior cesareans is found in over 60% of placenta accreta cases. Advanced maternal age and previous uterine surgery are other risk factors.

Symptoms:
Placenta accreta often causes no signs or symptoms during pregnancy, although vaginal bleeding during the third trimester might occur.

Diagnosis:
Placenta accreta is detected during an ultrasound.

Treatment:
If diagnosed with placenta accreta, your obstetrics care will be transferred to a team of specialists with a specific focus on placental disorders. This team includes specialists in maternal-fetal medicine, urology, gynecology oncology, interventional radiology, obstetrics anesthesia, critical care, nursing, and the blood bank. At time of delivery, hysterectomy is typically the recommended treatment.

Placenta Increta and Percreta

Placenta increta occurs when the placenta grows at least halfway through the wall of the uterus and attaches itself to the uterine muscle. Of all accreta, increta and percreta cases, increta occurs about 15% of the time.

A placenta percreta occurs when the placenta grows completely through the wall of the uterus; in some cases, placental tissue will continue to grow into nearby pelvic organs, including the bladder or colon. A placenta percreta is the least common type of the placental disorders, presenting itself in about 5% of all these cases.

The most severe complications occur during childbirth. In pregnancies without placental abnormalities, the placenta typically detaches from the uterine wall immediately after birth. With placenta increta and percreta, part or all of the placenta remains attached, which can cause severe blood loss after delivery. If the condition is diagnosed during pregnancy, patients will likely need an early cesarean delivery followed by hysterectomy.

Symptoms for Increta and Percreta:
Placenta increta and percreta often cause no signs or symptoms during pregnancy, although vaginal bleeding during the third trimester might occur.

Diagnosis:
These conditions usually are diagnosed using ultrasound. In some cases, your obstetrics team may recommend a magnetic resonance imaging (MRI). MRI is painless and safe for you and your baby.

Treatment:
If diagnosed with placenta increta or percreta, your obstetrics care will be transferred to a team of specialists with a specific focus on placental disorders. This team includes specialists in maternal-fetal medicine, urology, gynecology oncology, interventional radiology, obstetrics anesthesia, critical care, nursing, and the blood bank. At time of delivery, hysterectomy will likely be necessary.