It is frequently difficult to determine the exact causes of placenta abruptio. Definable, direct causes that result in placenta abruptio are quite rare (1 to 5%). They include mechanical factors such as abdominal trauma (for example, from an auto accident or fall), sudden loss in uterine volume as occurs with rapid loss of amniotic fluid or the delivery of a first twin, or an abnormally short umbilical cord (usually only a problem at the time of delivery).

Risk factors include the following:

• A placenta abruptio in a previous pregnancy. After one prior episode there is a 10 to 17% recurrence; after two previous episodes the chance of recurrence exceeds 20%.
• High blood pressure during pregnancy is associated with a placenta abruptio rate of 2.5 to 17.9%. This may be caused by pre-eclampsia, eclampsia, or other conditions. Approximately 50% of placenta abruptio cases severe enough to cause fetal death are associated with hypertension.

Other risk factors include increased maternal age; increased number of prior deliveries; increased uterine distention (as may occur with multiple pregnancies or abnormally large volume of amniotic fluid); diabetes in the pregnant woman; cigarette smoking; cocaine abuse; and drinking more than 14 alcoholic drinks per week during pregnancy.

The incidence of placenta abruptio, including any amount of placental separation prior to delivery, is about 1 out of 150 deliveries. The severe form, which results in fetal death, occurs only in about 1 out of 500 to 750 deliveries.

• Vaginal bleeding
• Abdominal pain
• Back pain

During a physical examination, uterine tenderness and/or increased uterine tone may be noticed. Bleeding during pregnancy may be visible or concealed.

Tests include:

• A CBC, may note decreased hematocrit or hemoglobin and platelets
• Prothrombin time test
• Partial thromboplastin time test
• Fibrinogen level test
• Abdominal ultrasound (may be done)

Treatment includes IV (intravenous) fluid replacement, blood transfusion, and careful monitoring of the mother for symptoms of shock and signs of fetal distress (fetal heart rate too high or too low, or abnormal fetal heart rate changes in relation to contractions).

An emergency cesarean section may be necessary for fetal distress or maternal bleeding. In the event of an immature fetus and evidence of only a small placental separation, the mother may be hospitalized for observation and released after several days if no evidence of progressing abruptio occurs.

If the fetus is mature, vaginal delivery may be chosen if maternal and fetal distress is minimal; otherwise, a cesarean section may be the preferred choice to protect the mother and the child.

The mother does not usually die from this condition. Maternal death rates in various parts of the world range from 0.5 to 5%. Early diagnosis of the condition and adequate treatment should decrease the maternal death rate even further. Fetal death rates range from 20-35 %. Upon hospital admission, no fetal heart tone is detectable in about 15% of cases.

Fetal distress appears early in the condition in approximately 50% of cases. The infants who live have a 40 to 50% chance of complications, which range from mild to severe. Concealed vaginal bleeding in pregnancy, excessive loss of blood resulting in shock, absence of labor, a closed cervix, and delayed diagnosis and treatment may increase the risk of maternal or fetal death.

Avoid drinking, smoking or using other drugs during pregnancy. Get early and continuous prenatal care.

Early recognition and proper management of conditions in the mother such as diabetes and high blood pressure also decrease the risk of placenta abruptio.