Why is placenta previa a concern?

The greatest risk of placenta previa is bleeding (or hemorrhage). Bleeding often occurs as the lower part of the uterus thins during the third trimester of pregnancy in preparation for labor. This causes the area of the placenta over the cervix to bleed. The more of the placenta that covers the cervical os (the opening of the cervix), the greater the risk for bleeding. Other risks include the following:

· Abnormal implantation of the placenta

· Slowed fetal growth

· Preterm birth

· Birth defects

What are the symptoms of placenta previa?

The most common symptom of placenta previa is vaginal bleeding that is bright red and not associated with abdominal tenderness or pain, especially in the third trimester of pregnancy. However, each woman may exhibit different symptoms of the condition or symptoms may resemble other conditions or medical problems. Always consult your doctor for a diagnosis.

How is placenta previa diagnosed?

In addition to a complete medical history and physical examination, an ultrasound (a test using sound waves to create a picture of internal structures) may be used to diagnose placenta previa. An ultrasound can show the location of the placenta and how much is covering the cervix. A vaginal ultrasound may be more accurate in diagnosis.

Although ultrasound may show a low-lying placenta in early pregnancy, only a few women will develop true placenta previa. It is common for the placenta to move upwards and away from the cervix as the uterus grows, called placental migration.

Treatment for placenta previa

Specific treatment for placenta previa will be determined by your doctor based on:

· Your pregnancy, overall health, and medical history

· Extent of the condition

· Your tolerance for specific medications, procedures, or therapies

· Expectations for the course of the condition

· Your opinion or preference

There is no treatment to change the position of the placenta. Once placenta previa is diagnosed, additional ultrasound examinations are often performed to track its location. Bed rest or hospital admission may be necessary. It may be necessary to deliver the baby, depending on the amount of bleeding, the gestational age, and condition of the fetus. Cesarean delivery is necessary for most cases of placenta previa. Severe blood loss may require a blood transfusion.

What is placental abruption?

Placental abruption is the premature separation of a placenta from its implantation in the uterus. Within the placenta are many blood vessels that allow the transfer of nutrients to the fetus from the mother. If the placenta begins to detach during pregnancy, there is bleeding from these vessels. The larger the area that detaches, the greater the amount of bleeding. Placental abruption occurs about once in every 100 births. It is also called abruptio placenta.

What causes placental abruption?

Other than direct trauma to the uterus such as in a motor vehicle accident, the cause of placental abruption is unknown. It is, however, associated with certain conditions, including the following:

· Previous pregnancy with placental abruption

· Hypertension (high blood pressure)

· Cigarette smoking

· Multiple pregnancy

· Sickle cell anemia

Why is placental abruption a concern?

Placental abruption is dangerous because of the risk of uncontrolled bleeding (hemorrhage). Although severe placental abruption is rare, other complications may include the following:

· Hemorrhage and shock

· Disseminated vascular coagulation (DIC)--a serious blood clotting complication.

· Poor blood flow and damage to kidneys or brain

· Stillbirth

· Hemorrhage during labor