Placenta Abruptio

Topic Overview

What is placenta abruptio?

Normally during pregnancy, the placenta is firmly attached to the inner wall of the uterus until the baby has been born. Placenta abruptio is the premature separation (abruption) of the placenta before childbirth. Since the round, flat placenta is a "lifeline" that supplies nutrients and oxygen to a fetus from the mother, an abruption can be life-threatening for the fetus, and sometimes for the mother as well. Placenta abruptio can lead to preterm birth, low birth weight [at or below 2500 g (5.5 lb)], and major maternal blood loss. In rare cases, severe placenta abruptio leads to fetal or newborn death.¹

See an illustration of placenta abruptio.

Placenta abruptio, also referred to as abruptio placenta or placental abruption, affects about 9 in 1,000 pregnancies.² It usually occurs in the third trimester of pregnancy, but it can occur any time after the 20th week. Up to 15 of every 100 abruptions aren't obvious until labour is in progress or after delivery.³

What causes placenta abruptio?

The causes of placenta abruptio are not well-understood, and some women develop it without any identifiable cause. However, you can reduce your risk by treating or avoiding some of the known risk factors that have been linked to placenta abruptio.

Common risk factors for placenta abruptio include:

• High blood pressure (140/90 mm Hg or higher), whether it is chronic or has been caused by the pregnancy (pregnancy-induced hypertension or pre-eclampsia). High blood pressure is the most common risk factor linked to placenta abruptio.⁴
• A past placental abruption. If you have had more than one abruption, your risk is greater.²
• Cigarette smoking. The more you smoke, the greater your risk of abruption. Up to 25 of every 100 placental abruptions are linked to cigarette smoking.⁵

Other risk factors for placenta abruptio include cocaine use; having a surgical scar or uterine fibroid where the placenta has attached; trauma to the uterus, as might occur in a car accident; and premature rupture of membranes for 24 hours or more, especially when there is an infection in the uterus.

What are common symptoms of placenta abruptio?

If you have developed placenta abruptio, you may notice one or more symptoms, including:

• Vaginal bleeding that is light or heavy, dark or bright red, depending on the location of the abruption and how long it's taken for the blood to pass.
• A tender, painful, or hard, rigid-feeling uterus.
• Signs of preterm labour, including regular contractions, lower back or abdominal ache or pain.

The amount of vaginal bleeding isn't a good measure of how severe an abruption is—heavy bleeding is sometimes the least apparent because the blood can remain trapped between the placenta and uterine wall. Heavy blood loss can cause symptoms of shock, including light-headedness, weakness, confusion, restlessness, and shallow, rapid breathing.

How is placenta abruptio diagnosed?

Your health professional may suspect placenta abruptio based on your symptoms, fetal heart rate pattern, an ultrasound, and possibly a blood test to check whether you're anemic from losing blood.

If you are suspected to have a placental abruption, you'll be observed for at least a few hours in the hospital. Your health professionals will need to assess how severe the abruption is, whether it is worsening, and whether it is affecting your fetus.

How is it treated?

Treatment depends on how severe the abruption is, how it is affecting your fetus, and how close your due date is. A mild abruption may resolve and can often be closely observed on an outpatient basis for the remainder of a pregnancy. A moderate to severe abruption requires hospitalization and constant fetal monitoring, and usually results in delivery, sometimes by emergency caesarean.

Frequently Asked Questions

Learning about placenta abruptio:	What is placenta abruptio? What causes placenta abruptio? What are symptoms of placenta abruptio? What increases my risk of placenta abruptio? What can I do to reduce my risk of placenta abruptio?
Being diagnosed:	When should I call my health professional about possible placenta abruptio? How is placenta abruptio diagnosed?
Getting treatment:	How is placenta abruptio treated?

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Author:	Kathe Gallagher, MSW Carrie Henley	Last Updated: May 15, 2006
Medical Review:	Joy Melnikow, MD, MPH - Family Medicine Tom Bailey, MD - Family Medicine William Gilbert, MD - Perinatology
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