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Bleeding in Pregnancy / Placenta Previa / Placental Abruption

Bleeding may occur at various times in pregnancy. Although bleeding is alarming, it may or may not be a serious complication. The time of bleeding in the pregnancy, the amount, and whether or not there is pain may vary depending on the cause.

Bleeding in the first trimester of pregnancy is quite common and may be due to the following:

Bleeding in late pregnancy (after about 20 weeks) may be due to the following:

What is placenta previa?

Placenta previa is a condition in which the placenta is attached close to or covering the cervix (opening of the uterus). Placenta previa occurs in about one in every 200 live births. There are three types of placenta previa:

Illustration demonstrating total placenta previa
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Illustration demonstrating partial placenta previa
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What causes placenta previa?

The cause of placenta previa is unknown, but it is associated with certain conditions including the following:

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 greater the risk for bleeding. Other risks include the following:

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 physician 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 physician based on:

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. 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 120 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:

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:

What are the symptoms of placental abruption?

The most common symptom of placental abruption is dark red vaginal bleeding with pain during the third trimester of pregnancy. It also can occur during labor. However, each woman may experience symptoms differently. Symptoms may include:

The symptoms of placental abruption may resemble other medical conditions. Always consult your physician for a diagnosis.

How is placental abruption diagnosed?

The diagnosis of placental abruption is usually made by the symptoms, and the amount of bleeding and pain. Ultrasound may also be used to show the location of the bleeding and to check the fetus. There are three grades of placental abruption, including the following:

Illustration demonstrating concealed bleeding during pregnancy
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Illustration demonstrating visible bleeding during pregnancy
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Sometimes placental abruption is not diagnosed until after delivery, when an area of clotted blood is found behind the placenta.

Treatment for placental abruption:

Specific treatment for placental abruption will be determined by your physician based on:

There is no treatment to stop placental abruption or reattach the placenta. Once placental abruption is diagnosed, a woman's care depends on the amount of bleeding, the gestational age, and condition of the fetus. Cesarean delivery is performed for most cases of placental abruption and emergency delivery may be needed if hemorrhage occurs. Severe blood loss may require a blood transfusion.

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Online Resources of High-Risk Pregnancy


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