Placental abruption

Placental abruption (abruptio placentae) is an uncommon yet serious complication of pregnancy. The placenta develops in the uterus during pregnancy. It attaches to the wall of the uterus and supplies the baby with nutrients and oxygen.

Placental abruption occurs when the placenta partly or completely separates from the inner wall of the uterus before delivery. This can decrease or block the baby's supply of oxygen and nutrients and cause heavy bleeding in the mother.

Placental abruption often happens suddenly. Left untreated, it endangers both the mother and the baby.

Placental abruption is most likely to occur in the last trimester of pregnancy, especially in the last few weeks before birth. Signs and symptoms of placental abruption include:

• Vaginal bleeding, although there might not be any
• Abdominal pain
• Back pain
• Uterine tenderness or rigidity
• Uterine contractions, often coming one right after another

Abdominal pain and back pain often begin suddenly. The amount of vaginal bleeding can vary greatly, and doesn't necessarily indicate how much of the placenta has separated from the uterus. It's possible for the blood to become trapped inside the uterus, so even with a severe placental abruption, there might be no visible bleeding.

In some cases, placental abruption develops slowly (chronic abruption), which can cause light, intermittent vaginal bleeding. Your baby might not grow as quickly as expected, and you might have low amniotic fluid or other complications.

Seek emergency care if you have signs or symptoms of placental abruption.

The cause of placental abruption is often unknown. Possible causes include trauma or injury to the abdomen — from an auto accident or fall, for example — or rapid loss of the fluid that surrounds and cushions the baby in the uterus (amniotic fluid).

Factors that can increase the risk of placental abruption include:

• Placental abruption in a previous pregnancy that wasn't caused by abdominal trauma
• Chronic high blood pressure (hypertension)
• Hypertension-related problems during pregnancy, including preeclampsia, HELLP syndrome or eclampsia
• A fall or other type of blow to the abdomen
• Smoking
• Cocaine use during pregnancy
• Early rupture of membranes, which causes leaking amniotic fluid before the end of pregnancy
• Infection inside of the uterus during pregnancy (chorioamnionitis)
• Being older, especially older than 40

Placental abruption can cause life-threatening problems for both mother and baby.

For the mother, placental abruption can lead to:

• Shock due to blood loss
• Blood clotting problems
• The need for a blood transfusion
• Failure of the kidneys or other organs resulting from blood loss
• Rarely, the need for hysterectomy, if uterine bleeding can't be controlled

For the baby, placental abruption can lead to:

• Restricted growth from not getting enough nutrients
• Not getting enough oxygen
• Premature birth
• Stillbirth

You can't prevent placental abruption, but you can decrease certain risk factors. For example, don't smoke or use illegal drugs, such as cocaine. If you have high blood pressure, work with your health care provider to monitor the condition.

Always wear your seatbelt when in a motor vehicle. If you've had abdominal trauma — from an auto accident, fall or other injury — seek immediate medical help.

If you've had a placental abruption, and you're planning another pregnancy, talk to your health care provider before you conceive to see if there are ways to reduce the risk of another abruption.