How would you manage thrombocytopenia (low platelet count) in a healthy 28-week gestation pregnancy?

Management of Thrombocytopenia in a Healthy 28-Week Gestation Pregnancy

Management of thrombocytopenia in a 28-week pregnancy should focus on determining the underlying cause, monitoring platelet counts regularly, and initiating treatment only when clinically indicated based on platelet count thresholds and bleeding risk. 1

Diagnostic Approach

First, determine the underlying cause of thrombocytopenia:

• Perform blood pressure measurement and liver function tests to rule out preeclampsia and HELLP syndrome 1
• Examine peripheral blood smear to exclude other causes of thrombocytopenia 1
• Consider HIV testing if risk factors are present 1
• Note that bone marrow examination is not required for diagnosis of ITP in pregnancy 1
• Maternal antiplatelet antibody testing has no value in routine diagnosis 1

Common causes to consider:

• Gestational thrombocytopenia (75% of cases) - typically mild (>70×10^9/L), occurs in late gestation 1
• Immune thrombocytopenia (ITP)
• Preeclampsia/HELLP syndrome
• Other causes: antiphospholipid syndrome, thrombotic thrombocytopenic purpura, hemolytic uremic syndrome 1

Monitoring Protocol

• Initially monitor platelet counts every 2-4 weeks 1
• Increase frequency of monitoring as delivery approaches, particularly in the third trimester when platelet counts may fall 1
• Monitor trend of platelet counts, not just absolute values - a rapidly falling count requires closer observation than stable low levels 2

Treatment Algorithm

1. No treatment required if:

   • Platelet count >50×10^9/L
   • No bleeding symptoms
   • No procedures planned 1

2. Treatment indicated if:

   • Patient has bleeding symptoms
   • Platelet count <50×10^9/L
   • Procedures are planned
   • Patient is approaching delivery 1

3. First-line treatment options:

   • Prednisone 10-20 mg/day (adjust to minimum effective dose) 1
   • IVIg if corticosteroids are ineffective, cause significant side effects, or more rapid platelet increase is needed 2

4. For refractory cases:

   • Combining first-line treatments may be appropriate in the weeks before delivery 2
   • High-dose methylprednisolone (1000 mg) possibly combined with IVIg 2
   • Azathioprine is safe during pregnancy but response is slow 2

5. Medications to avoid due to teratogenicity:

   • Vinca alkaloids
   • Rituximab
   • Danazol
   • TPO-receptor agonists
   • Most immunosuppressive drugs (except azathioprine) 1

Delivery Planning

• Target platelet counts for delivery:

  • ≥50×10^9/L for cesarean section
  • ≥75-100×10^9/L for epidural/spinal anesthesia 2, 1

• For regional anesthesia:

  • No changes to routine practice required until platelet count drops below 50×10^9/L 2
  • For counts <50×10^9/L, careful risk-benefit analysis needed with multidisciplinary discussion 2
  • Spinal may be safer than epidural blockade due to smaller needle size 2
  • An experienced operator is required 2

• Mode of delivery should be determined by obstetric indications rather than platelet count alone 1

• Avoid procedures during labor with increased hemorrhagic risk:

  • Fetal scalp electrodes
  • Fetal blood samples
  • Ventouse delivery
  • Rotational forceps 2

Neonatal Considerations

• Obtain cord blood platelet count after delivery 2
• Perform transcranial ultrasonography on neonates with platelet counts <50×10^9/L 1
• Avoid intramuscular injections in the neonate until platelet count is known 2
• For neonates with clinical hemorrhage or platelet counts <20×10^9/L, consider treatment with IVIg 1 g/kg 2

Multidisciplinary Care

• Establish collaboration among obstetrician, hematologist, anesthesiologist, and neonatologist 1
• Provide reassurance that pregnancy in women with ITP can generally proceed safely with low hemorrhagic risk for both mothers and infants 1

Important Caveats

• Maternal platelet count cannot reliably predict fetal platelet count 2, 1
• Attempts to measure fetal platelet count before delivery (cordocentesis) carry a 1-2% fetal mortality risk and are not recommended 2
• Despite thrombocytopenia, ITP in pregnancy may be associated with a prothrombotic state, so VTE prophylaxis should be considered 2