What are the signs and symptoms of placental abruption?

Signs and Symptoms of Placental Abruption

Placental abruption typically presents with vaginal bleeding and abdominal pain, often accompanied by uterine contractions and abnormal fetal heart rate patterns. 1, 2

Clinical Presentation

Cardinal Signs

• Vaginal bleeding
  • Present in most but not all cases
  • May be concealed if blood is trapped behind the placenta
  • Amount varies from minimal spotting to profuse hemorrhage 3
• Abdominal pain
  • Often described as sudden onset
  • May be localized or diffuse
  • Typically moderate to severe in intensity 2
• Uterine tenderness/rigidity
  • Uterus feels firm or "woody" on palpation
  • May have increased uterine tone 1
• Uterine contractions
  • Often frequent and painful
  • May mimic preterm labor 2

Associated Findings

• Abnormal fetal heart rate patterns
  • Late decelerations
  • Decreased variability
  • Bradycardia in severe cases 2
• Maternal hemodynamic instability
  • Tachycardia
  • Hypotension (in severe cases)
  • Signs of shock in massive abruption 1
• Back pain (less common)
• Fetal distress or absence of fetal movement 4

Important Diagnostic Considerations

Clinical Diagnosis

• Placental abruption is primarily a clinical diagnosis 4
• Severity ranges from asymptomatic (diagnosed only after delivery by placental examination) to massive abruption causing fetal death and severe maternal morbidity 5

Ultrasound Findings

• Ultrasound has limited sensitivity (only detects approximately 50% of abruptions) 3
• Potential findings include:
  • Retroplacental clot (hypoechoic or hyperechoic area)
  • Placental thickening
  • Jello-like movement of the placenta 3
• Color Doppler can be invaluable:
  • Helps identify areas with no blood flow contiguous with the placenta
  • Can distinguish acute clot from placental tissue 3

Laboratory Findings

• Complete blood count may show anemia
• Coagulation studies may reveal disseminated intravascular coagulation (DIC) in severe cases
• Kleihauer-Betke test has limited diagnostic value 4

Risk Stratification

Severity Assessment

• Mild: Minimal vaginal bleeding, mild uterine tenderness, stable maternal vital signs, reassuring fetal status
• Moderate: Moderate vaginal bleeding, moderate uterine tenderness, stable maternal vital signs, possible fetal distress
• Severe: Profuse vaginal bleeding, marked uterine tenderness, maternal hemodynamic instability, fetal distress or demise 1

High-Risk Features

• Significant bleeding with hemodynamic changes
• Evidence of coagulopathy
• Fetal distress
• Placental separation >50% (associated with high fetal mortality) 4

Common Pitfalls

• Concealed hemorrhage: Blood may be trapped behind the placenta with minimal or no vaginal bleeding, leading to underestimation of severity 5
• Reliance on ultrasound alone: Given its limited sensitivity, a negative ultrasound does not exclude abruption 3
• Confusion with other causes of bleeding: Placenta previa, vasa previa, and cervical causes of bleeding may present similarly 3
• Delayed recognition of coagulopathy: DIC can develop rapidly in severe abruption 6

Key Differences from Other Causes of Bleeding

• Placenta previa: Typically painless bleeding; placental location over cervical os visible on ultrasound 3
• Vasa previa: Painless bleeding; vessels visible over cervical os on Doppler 3
• Uterine rupture: More common in patients with prior cesarean delivery; may have more dramatic maternal collapse 3

Prompt recognition of placental abruption is critical as it is associated with significant maternal morbidity (hemorrhage, need for transfusion, DIC, renal failure) and perinatal mortality and morbidity (preterm birth, asphyxia, stillbirth) 6.