Placental abruption is the premature detachment of a normally positioned placenta from the wall of the uterus, usually after 20 weeks of pregnancy.
- Women may have vaginal bleeding and/or severe abdominal pain and go into shock.
- When the placenta detaches too soon, the fetus may not grow as much as expected or may even die.
- Doctors diagnose placental abruption based on symptoms and sometimes do ultrasonography to confirm the diagnosis.
- Limiting activity may be all that is needed, but if bleeding continues, if the fetus is in danger, or if the pregnancy is at term, the baby is delivered as soon as possible.
Pregnancy complications, such as placental abruption, are problems that occur only during pregnancy. They may affect the woman, the fetus, or both and may occur at different times during the pregnancy. However, most pregnancy complications can be effectively treated.
The placenta may detach incompletely (sometimes just 10 to 20%) or completely. The cause is unknown.
Detachment of the placenta occurs in 0.4 to 1.5% of all pregnancies.
Problems With the Placenta
Normally, the placenta is located in the upper part of the uterus, firmly attached to the uterine wall until after delivery of the baby. The placenta carries oxygen and nutrients from the mother to the fetus.
In placental abruption (abruptio placentae), the placenta detaches from the uterine wall prematurely, causing the uterus to bleed and reducing the fetus’s supply of oxygen and nutrients. Women who have this complication are hospitalized, and the baby may be delivered early.
In placenta previa, the placenta is located over or near the cervix, in the lower part of the uterus. Placenta previa may cause painless bleeding that suddenly begins late in pregnancy. The bleeding may become profuse. The baby is usually delivered by cesarean.
Risk factors (conditions that increase the risk of a disorder) for placental abruption include the following:
- High blood pressure (including preeclampsia, a type of high blood pressure that develops during pregnancy)
- Use of cocaine
- Older age
- Vasculitis or other blood vessel disorders
- Previous placental abruption
- Abdominal injury
- Blood clotting disorders such as antiphospholipid antibody syndrome
- Use of tobacco
- Infection in the tissues around the fetus (intra-amniotic infection)
- Premature rupture of the membranes, especially when there is too much amniotic fluid around the fetus (polyhydramnios)
- Lack of oxygen to the placenta
Symptoms of placental abruption depend on the degree of detachment and the amount of blood lost (which may be massive).
Symptoms may include sudden continuous or crampy abdominal pain, tenderness when the abdomen is gently pressed, and dangerously low blood pressure (shock). Some women have no symptoms.
The uterus bleeds from the site where the placenta has detached. The blood may pass through the cervix and out the vagina as an external hemorrhage, or the blood may be trapped behind the placenta as a concealed hemorrhage. Thus, women may or may not have vaginal bleeding. If bleeding occurs, the blood may be bright or dark red, and bleeding may be continuous or spotty.
Premature detachment of the placenta sometimes leads to severe blood loss with widespread clotting inside the blood vessels (disseminated intravascular coagulation), kidney failure, and bleeding into the walls of the uterus, especially in pregnant women who also have preeclampsia.
When the placenta detaches, the supply of oxygen and nutrients to the fetus may be reduced. If detachment occurs suddenly and greatly reduces the oxygen supply, the fetus may die. If it occurs gradually and less extensively, the fetus may not grow as much as expected (intrauterine growth restriction) or there may be too little amniotic fluid (oligohydramnios). Gradual detachment may cause less abdominal pain and have a lower risk of shock in the mother than sudden detachment, but the risk of subsequent premature rupture of the membranes is increased.
- A doctor's evaluation
- Sometimes ultrasonography
Doctors suspect and usually diagnose premature detachment of the placenta based on symptoms. Ultrasonography may help doctors confirm the diagnosis of premature detachment and distinguish it from placenta previa, which can cause similar symptoms. Ultrasonography may be done by placing a handheld device on the abdomen (called abdominal ultrasonography) or inside the vagina (called transvaginal ultrasonography).
Doctors may check for preeclampsia because it can increase the risk of problems.
To check for problems that premature detachment can cause, doctors may do blood tests and may monitor the fetus's heart rate.
- Sometimes hospitalization and modified activity
- Sometimes prompt delivery
A woman with premature detachment of the placenta may be hospitalized depending on how severe the symptoms are and how long the pregnancy has lasted. Sometimes the only treatment needed is modified activity (modified bed rest). Modified activity means that the woman should stay off her feet most of the day. Doctors also advise against sexual intercourse.
Modified activity with hospitalization is appropriate if all of the following are present:
- The bleeding does not threaten the life of the mother or fetus but continues.
- The fetus's heart rate is normal.
- The pregnancy is preterm (less than 37 weeks).
This approach enables doctors to closely monitor the woman and fetus and, if needed, rapidly treat them. Usually, when the risk of early delivery is high, corticosteroids are also recommended (to help the fetus's lungs mature). If symptoms lessen and the fetus is not in danger, the woman may be discharged from the hospital.
Delivery is usually done as soon as possible if any of the following is present:
- Bleeding continues or worsens.
- The fetus's heart rate is abnormal (suggesting that the fetus is not getting enough oxygen).
- The pregnancy is at term (37 weeks or more).
If vaginal delivery is not possible, a cesarean delivery is done.
If the woman goes into shock or disseminated intravascular coagulation develops, the woman is given blood transfusions and monitored in an intensive care unit.