Abruptio placentae


Background: Abruptio placentae is defined as premature separation of the placenta from the uterus. Clinically it most often presents with bleeding, uterine contractions, and fetal distress. It is a significant cause of third trimester bleeding and is associated with both fetal and maternal morbidity and mortality. It must be entertained as a diagnosis anytime third trimester bleeding is encountered.


Pathophysiology: As the placenta separates from the uterus, hemorrhage ensues into the decidua basalis. Vaginal bleeding usually follows, although it is possible to have a concealed hemorrhage where the blood pools behind the placenta.

If the bleeding continues, fetal and maternal distress may develop with fetal and then maternal death if appropriate interventions do not occur. The primary cause of placental abruption is unknown, but there are multiple risk factors that have been identified.



Mortality/Morbidity: Maternal or fetal

The overall fetal mortality rate for placental abruption is between 20-40%, depending on the extent of the abruption. It is higher in patients with a significant smoking history. Fetal morbidity is caused by the insult of the abruption itself, as well as issues of prematurity.

Placental abruption is currently responsible for approximately 6% of maternal deaths. Maternal complications include:

Race: Placental abruption is more common in African American women than in either Caucasian or Latin American women. However, it is unclear as to whether this is the result of socioeconomic, genetic, or a combination of such factors.

Sex: This is a disease observed only in pregnancy.

Age: An increased risk of placental abruption has been demonstrated in patients younger than 20 years or older than 35 years.


History: Symptoms may include vaginal bleeding, contractions, abdominal tenderness, and decreased fetal movement. It is important to elicit any history of trauma, such as assault, abuse, or a motor vehicle accident. A quick review of the patient's prenatal course, such as a known history of a placenta previa, may help lead you to the correct diagnosis. Questioning the patient about symptoms of cocaine use, a history of hypertension or tobacco abuse is also important.

Physical: The physical examination for a patient who is bleeding is targeted at determining the origin of the hemorrhage. At the same time, it is imperative that the patient be stabilized quickly. With placental abruption the relatively stable patient may progress quickly to a state of hypovolemic shock.

Causes: While there are multiple risk factors for abruptio placentae, there are only a few events that have been closely linked to this condition, including:


Other notable risk factors include:



Other Problems to be Considered:

Placenta previa
Preterm labor
Labor with bloody show
Vasa previa
Vaginal trauma
Malignancy (rare)


Lab Studies:

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Histologic Findings: After delivery of the placenta, a retroplacental clot may be seen. Another possible finding involves extravasation of blood into the myometrium, which produces a purple discoloration of the uterine serosa that is known as a Couvelaire uterus.


Medical Care: Inpatient admission is required if abruptio placentae is suspected.

Surgical Care:


Diet: The patient should be made NPO if emergent delivery is a possibility.

Activity: Patients who are diagnosed with a chronic abruption and are preterm may be placed on modified bedrest and monitored closely for any signs of maternal or fetal distress, which could necessitate delivery. Again, consultation with MFM is advised for conservative management of abruptio placentae.


Tocolysis is considered controversial in the management of placental abruption and is only considered in patients (1) who are hemodynamically stable, (2) in whom no evidence of fetal jeopardy exists, and (3) in whom a preterm fetus may benefit from corticosteroids or delay of delivery.

Even in patients with these criteria, consultation with a maternal fetal medicine (MFM) specialist is important. Tocolysis must be undertaken with caution as maternal or fetal distress can develop rapidly. In general, magnesium sulfate is used for tocolysis rather than beta-sympathomimetic agents. The latter has significant undesirable cardiovascular side effects in these patients.

Drug Category: Tocolytics -- Tocolytics may allow for effective administration of glucocorticoids to the preterm fetus to accelerate fetal lung maturation. In a chronic abruption, it may also allow for delay of delivery to a gestational age when complications of prematurity are less severe.

Drug Name
Magnesium Sulfate -- DOC for tocolysis in patients with placental abruption.
Adult Dose 4-6gm IV bolus over 20 min
2-4 gm/h maintenance rate, titrated as needed to suppress contractions
Pediatric Dose Not established
Contraindications Documented hypersensitivity; hypocalcemia; myasthenia gravis, renal failure
Interactions Concurrent use with nifedipine may cause hypotension and neuromuscular blockade; may increase neuromuscular blockade seen with aminoglycosides and potentiate neuromuscular blockade produced by tubocurarine, vecuronium, and succinylcholine; may increase CNS effects and toxicity of CNS depressants, betamethasone, and cardiotoxicity of ritodrine
Pregnancy B - Usually safe but benefits must outweigh the risks.
Precautions Adverse effects include flushing, blurry vision, headaches, and nausea; more serious adverse effects, seen only at toxic levels, include pulmonary edema, respiratory depression, cardiac arrest, maternal tetany, profound hypotension
to reverse effects of magnesium sulfate (calcium gluconate 1 g slow IV push may be given)

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