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:
Miscarriage (pregnancy loss)
Ectopic pregnancy (pregnancy in the fallopian tube)
Gestational trophoblastic disease (a rare condition that may be cancerous in which a grape-like mass of fetal and placental tissues develops)
Implantation of the placenta in the uterus
Infection
Bleeding between the uterine wall and placental membrane (subchorionic hemorrhage or hematoma)
Normal changes in the cells of the cervix due to pregnancy
Bleeding in late pregnancy (after about 20 weeks) may be due to the following:
Placenta previa (placenta is near or covers the cervical opening)
Placental abruption (placenta detaches prematurely from the uterus)
Unknown cause
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:
Total placenta previa. The placenta completely covers the cervix.
Partial placenta previa. The placenta is partially over the cervix.
Marginal placenta previa. The placenta is near the edge of the cervix.
What causes placenta previa?
The cause of placenta previa is unknown, but it is associated with certain conditions including the following:
Women who have scarring of the uterine wall from previous pregnancies
Women who have fibroids or other abnormalities of the uterus
Women who have had previous uterine surgeries or cesarean deliveries
Older mothers (over age 35)
African-American or other minority race mothers
Cigarette smoking
Placenta previa in a previous pregnancy
Being pregnant with a male fetus
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
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. Some women may not have vaginal bleeding that is detectable, but there may be bleeding inside the uterus. Symptoms may include:
Vaginal bleeding
Abdominal pain
Uterine contractions that do not relax
Blood in amniotic fluid
Nausea
Thirst
Faint feeling
Decreased fetal movements
The symptoms of placental abruption may resemble other medical conditions. Always consult your doctor 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:
Grade 1. Small amount of vaginal bleeding and some uterine contractions, no signs of fetal distress or low blood pressure in the mother.
Grade 2. Mild to moderate amount of bleeding, uterine contractions, the fetal heart rate may shows signs of distress.
Grade 3. Moderate to severe bleeding or concealed (hidden) bleeding, uterine contractions that do not relax (called tetany), abdominal pain, low blood pressure, fetal death.
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 doctor based on:
Your pregnancy, overall health, and medical history
Extent of the disease
Tolerance for specific medications, procedures, or therapies
Expectations for the course of the disease
Your opinion or preference
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. Vaginal delivery may be possible if the fetus is tolerating labor. If placental abruption is affecting the fetus, then cesarean delivery may be necessary. Severe blood loss may require a blood transfusion.