Abruptio Placentae Definition
Abruptio placentae (placental abruption) is the partial or complete premature separation of the normally implanted placenta from the uterine wall before delivery of the fetus. 1
Pathophysiology
The key pathophysiologic mechanism involves hemorrhage at the decidual-placental interface, resulting from the interaction of chronic processes (decidual and uteroplacental vasculopathy) and acute processes (shearing forces applied to the abdomen). 2, 3
Clinical Presentation
The classic triad of clinical manifestations includes:
- Vaginal bleeding (typically dark blood, though bleeding may be concealed) 1, 2, 4
- Abdominal pain with uterine tenderness 2, 4
- Uterine contractions with increased tone 2, 4
- Abnormal fetal heart rate patterns ranging from tachycardia to bradycardia or absent heart tones 3, 4
Epidemiology and Severity
- Occurs in 0.4% to 1.2% of all pregnancies 5, 3, 4
- Nearly half of cases occur at term gestations 3
- Abruption involving more than 50% of the placenta is frequently associated with fetal death 5
Maternal and Fetal Consequences
Larger placental abruptions cause uteroplacental insufficiency, ischemia, chronic hypoxemia, and/or fetal death. 1 The maternal effects depend primarily on severity, while fetal effects are determined by both severity and gestational age. 5
Major Maternal Complications:
- Hemorrhagic shock 2, 3
- Disseminated intravascular coagulopathy (DIC) 5, 2
- Renal failure 2, 3
- Maternal anemia 6
- Uterine rupture (rare) 6
Fetal/Neonatal Complications:
Diagnostic Limitations
The diagnosis of abruption is primarily clinical, as ultrasonography has significant limitations and likely identifies at most 50% of cases, though likely many fewer. 1 An acute clot can have echogenicity similar to the placenta, making diagnosis challenging especially before clot organization. 1 Central abruption is associated with worse perinatal outcomes than marginal placental separation. 1
Risk Factors
Major risk factors include: