AUTHOR: Kelly Ruhstaller, MD
DefinitionAbruptio placentae is the separation of placenta from the uterine wall before delivery of the fetus. The condition occurs in approximately 1% of pregnancies. There are three classes of abruption (Fig. 1) based on maternal and fetal status, including an assessment of uterine contractions, quantity of bleeding, fetal heart rate monitoring, and abnormal coagulation studies (fibrinogen, prothrombin time, partial thromboplastin time).
- Grade I: Mild vaginal bleeding, uterine irritability, stable vital signs, reassuring fetal heart rate, normal coagulation profile (fibrinogen 450 mg/dl). Approximately half of abruptions are grade I.
- Grade II: Moderate vaginal bleeding, hypertonic uterine contractions, orthostatic blood pressure measurements, unfavorable fetal status, fibrinogen 150 to 250 mg. Approximately a quarter of abruptions are grade II.
- Grade III: Severe bleeding (may be concealed), hypertonic uterine contractions, overt signs of hypovolemic shock, fetal death, thrombocytopenia, fibrinogen <150 mg/dl. Approximately a quarter of abruptions are grade III.
Figure 1 Classification of placental abruption.
From Magowan BA: Clinical obstetrics & gynecology, ed 4, 2019, Elsevier.
SynonymPremature separation of placenta
Placental abruption
ICD-10CM CODES | O45.8X1 | Other premature separation of placenta, first trimester | O45.8X2 | Other premature separation of placenta, second trimester | O45.8X3 | Other premature separation of placenta, third trimester | O45.8X9 | Other premature separation of placenta, unspecified trimester | O45.91 | Premature separation of placenta, unspecified, first trimester | O45.92 | Premature separation of placenta, unspecified, second trimester | O45.93 | Premature separation of placenta, unspecified, third trimester |
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Epidemiology & DemographicsIncidence (In U.S.)9.6/1000 births; 80% occur before the onset of labor.
Prevalence5% to 17%, some studies showing a 5- to 10-fold increase in risk; with two prior episodes, 25%.
Risk FactorsHypertension (greatest association), trauma, polyhydramnios, multifetal gestation, smoking, use of cocaine, chorioamnionitis, preterm premature rupture of membranes. Table 1 summarizes placental abruption risk factors.
TABLE 1 Placental Abruption Risk Factors
- Increasing parity or maternal age
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- Preterm premature rupture of membranes
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- Rapid uterine decompression associated with multiple gestation and polyhydramnios
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- Inherited or acquired thrombophilia
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- Uterine malformations or fibroids
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- Placental abnormalities or ischemia
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From Gabbe SG: Obstetrics, ed 6, Philadelphia, 2012, Saunders.
Physical Findings & Clinical Presentation
- Triad of uterine bleeding (concealed or per vagina), hypertonic uterine contractions or signs of preterm labor, and evidence of fetal compromise exists.
- More than 80% of cases have external bleeding; 20% of cases have no bleeding but have indirect evidence of abruption, such as failed tocolysis for preterm labor.
- Tetanic uterine contractions are found in only 17%.
Etiology
- Primary etiology: Unknown
- Hypertension: Found in 40% to 50% of grade III abruptions
- Rapid decompression of uterine cavity, as can occur in polyhydramnios or multifetal gestation
- Blunt external trauma (motor vehicle accident, spousal abuse)