creation date: 2026-01-15 19:30
tags: Pathologies
Placental Abruption
Background
Definitions
Placental abruption is defined as the premature separation of the placenta from the decidua at or after 20 weeks of gestation.
Prior to 20 weeks, a placental separation is considered to be part of spontaneous abortion unless it is associated with disseminated intravascular coagulation, in which it is considered an early abruption.
Etiology and Risk Factors
Major risk factors that may lead to abruption are:
- Previous abruption
- Hypertension
- Structural uterine abnormalities
- Cocaine and cigarette use
- Genetic factor (slight component of FHx)
Pathogenesis
The immediate cause of placental abruption is the rupture of maternal vessels in the decidua basalis.
In cases of acute abruption, high-pressure hemorrhage from the arteries in the centre of the placenta dissections through the placenta-dicidual interface causing severe maternal bleeding, DIC, and FHR problems. This may be preceded by:
- Sudden mechanical events (eg. trauma)
- Rapid uterine decompression (eg. birth of first twin or rapid release of polyhydramnios)
In cases of chronic abruption, abnormal spiral arteries lead to decidual necrosis and inflammation/infarction. This causes low-pressure venous hemorrhage in the periphery and are typically self-limited. Manifestations are relatively milder with light spotting, oligohydramnios, and fetal growth restriction due to decreased perfusion.
In abruption, bleeding leads to the release of tissue factor (thromboplastin) from decidual cells which generates thrombin. Thrombin can induce uterine hypertonus and contraction and dysregulated coagulation.
Clinical Presentation
Signs & Symptoms
Acute abruption classically presents with:
- Sudden onset of vaginal bleeding
- Mild to moderate abdominal pain which may be on the back as well if placenta is posterior
- Uterine contractions (high frequency, low amplitude; but labour-like possible too)
In 10-20% of cases, patients may present with only uterine contraction and/or irritability. There would be no or minimal vaginal bleeding due to blood being trapped.
Chronic abruption presents with:
- Relatively light, chronic, intermittent bleeding
- Oligohydramnios, fetal growth restriction, and/or preeclampsia
History & Physical Exam
Speculum exam should appreciate extent of vaginal bleeding. Palpation of uterus for tenderness and tone is also performed.
Diagnosis
Criteria
Diagnosis of placental abruption is a clinical diagnosis. Ultrasound should be used to exclude other disorders of vaginal bleeding.
Work-up
There are no testing which can definitively confirm abruption.
Laboratory studies
- CBC
- Type and screen
- Coagulation studies
- Complete metabolic panel with creatinine
- Liver chemistries (if preeclampsia/HELLP syndrome suspected)
Ultrasound
Findings may include:
- Retroplacental hematoma
- Subchorionic collection of fluid
- Echogenic debris in amniotic fluid
- Thickened placenta
Differential
Alternative diagnoses for vaginal bleeding with abdominal pain and contractions include:
- Labour (eval: usually more gradual onset)
- Placenta previa (eval: painless)
- Uterine rupture (eval: cessation of uterine contraction and recession of presenting part)
- Subchorionic hematoma (eval: ultrasound)
Red Flags / Complications
The complications depend on the severity of the separation.
Maternal
Excessive blood loss and desseminated intravascular coagulation which can lead to:
- Hypovolemic shock
- Acute kidney injury
- Respiratory distress syndrome
- Multiorgan failure
- Peripartum hysterectomy
Fetal and neonatal
Increased morbidity and mortality relating to hypoxemia and/or preterm birth. In cases of chronic abruption, growth restriction/SGA may occur.
Management
Initial Approach
Immediate management consist of:
- Maternal and fetal monitoring
- IV access and fluids to maintain urine output
- Supplemental oxygen as needed
- Blood products as needed (if blood loss exceeds 500 mL)
Medications should be administered if indicated:
- If delivering within 24-48 hrs, magnesium sulfate and GBS prophylaxis
- If gestation <34 weeks, antenatal corticosteroids
- If patient is RhD-negative, anti-D immune globulin
Delivery
The modality of delivery depends on the stability of the fetus and mother.
In cases of instability, C-section is preferred whether fetus is alive or not.
In a stable mother, vaginal birth is typically preferred. The decision to undergo expectant management or induction depends on the stability of the fetus (more stable allows for expectant).