Placenta abruptio is separation of the placenta (the organ that nourishes the fetus) from the site of uterine implantation before delivery of the fetus.

It is frequently difficult to determine the exact causes of placenta abruptio. Direct causes that result in placenta abruptio are quite rare, but include injury to the abdomen from an auto accident or fall, sudden loss in uterine volume (can occur with rapid loss of amniotic fluid or the delivery of a first twin), or an abnormally short umbilical cord.

Risk factors include:

• A placenta abruptio in a previous pregnancy. After one prior episode there is a 10 - 17% recurrence; after two previous episodes the chance of recurrence exceeds 20%.
• High blood pressure during pregnancy. Approximately 50% of placenta abruptio cases severe enough to cause fetal death are associated with high blood pressure.
• Increased maternal age
• Large number of prior deliveries
• Increased uterine distention (as may occur with multiple pregnancies or abnormally large volume of amniotic fluid)
• Diabetes
• Cigarette smoking
• Cocaine use
• 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

Tests may include:

• Pelvic exam
• CBC, may note decreased hematocrit or hemoglobin and platelets
• Prothrombin time test
• Partial thromboplastin time test
• Fibrinogen level test
• Abdominal ultrasound