Placental abruption (abruptio placentae) 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.
Bed rest may be all that is needed, but if bleeding continues, if the fetus is in danger, or if the pregnancy is near term, the baby is delivered as soon as possible.
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 deliveries.
The following increase risk:
High blood pressure (including preeclampsia, a type of high blood pressure that develops during pregnancy)
Use of cocaine
Vasculitis or other blood vessel disorders
Previous placental abruption
Blood clotting disorders
Use of tobacco
Infection in the tissues around the fetus (chorioamnionitis)
Premature rupture of membranes, particularly if there is too much amniotic fluid around the fetus (polyhydramnios)
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.
Symptoms 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 pressed, and dangerously low blood pressure (shock). Some women have no symptoms.
The uterus bleeds from the site where the placenta was attached. The blood may pass through the cervix and out the vagina as an external hemorrhage, or it may be trapped behind the placenta as a concealed hemorrhage. Thus, women may or may not have vaginal bleeding.
Premature detachment of the placenta can lead to 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 or there may be too little amniotic fluid (oligohydramnios). Gradual detachment may cause less abdominal pain and have a lower risk of shock than sudden detachment, but the risk of preeclampsia and premature rupture of the membranes is increased.
Doctors suspect and usually diagnose premature detachment of the placenta based on symptoms. Ultrasonography may help confirm the diagnosis.
To check for problems that premature detachment can cause, doctors may do blood tests and may monitor the fetus's heart rate.
A woman with premature detachment of the placenta is hospitalized. The usual treatment is bed rest. This approach enables doctors to closely monitor the woman and fetus and, if needed, rapidly treat them. Women may be given corticosteroids to help the fetus's lungs mature in case an early delivery is needed. If symptoms lessen, the woman is encouraged to walk and may be discharged from the hospital.
If bleeding continues or worsens, if the fetus's heart rate is abnormal (suggesting that the fetus is not getting enough oxygen) or if the pregnancy is near term, delivery is usually done as soon as possible. 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.