How is pregnancy-induced thrombocytopenia managed in pregnant women?

Management of Pregnancy-Induced Thrombocytopenia

Most pregnancy-related thrombocytopenia is gestational thrombocytopenia requiring only observation, but treatment thresholds and interventions depend on platelet count, trimester, and bleeding symptoms—not on distinguishing gestational thrombocytopenia from ITP, which is often impossible during pregnancy. 1, 2

Diagnostic Approach

Key Historical and Clinical Features

A thorough history distinguishing gestational thrombocytopenia from ITP is essential: 3

• Prior thrombocytopenia when not pregnant strongly suggests ITP rather than gestational thrombocytopenia 3
• Timing matters critically: Thrombocytopenia in the first or second trimester raises suspicion for ITP or other pathology, while late third-trimester onset suggests gestational thrombocytopenia 1, 2
• Gestational thrombocytopenia characteristics: asymptomatic, mild (typically >70,000/μL, often 130,000-150,000/μL), occurs in late gestation, not associated with fetal thrombocytopenia, resolves spontaneously postpartum 3

Critical First-Trimester Distinction

Thrombocytopenia with microangiopathic hemolytic anemia in the first trimester demands immediate ADAMTS13 testing to rule out thrombotic thrombocytopenic purpura (TTP), as gestational thrombocytopenia, preeclampsia, and HELLP syndrome are predominantly third-trimester complications. 4

Essential Exclusions

Before diagnosing gestational thrombocytopenia or ITP, exclude: 1, 2

• Preeclampsia and HELLP syndrome: Check blood pressure and liver function tests 1, 2
• DIC, acute fatty liver of pregnancy, folate deficiency, antiphospholipid antibody syndrome 1, 2

Unnecessary Testing

• Bone marrow examination is not required 1
• Antiplatelet antibody testing has no diagnostic value 1
• Fetal blood sampling by cordocentesis should never be performed—it carries 1-2% fetal mortality risk, at least as high as the risk it attempts to prevent 1

Treatment Thresholds by Platelet Count

No Treatment Required

Observation alone for platelet counts ≥50,000/μL throughout pregnancy 2

Patients with platelets ≥30,000/μL do not routinely require treatment in the first two trimesters 1

Treatment Indicated

Treat when: 1, 2

• Platelet count <10,000/μL at any gestational age, even if asymptomatic 1, 2
• Platelet count 10,000-30,000/μL with active bleeding, regardless of trimester 1, 2
• Platelet count <20,000-30,000/μL, even if asymptomatic 1
• Any symptomatic bleeding, regardless of platelet count 1

First-Line Treatment Options

Corticosteroids

Prednisone 10-20 mg/day is the recommended initial treatment, adjusted to the minimum dose that maintains hemostatic platelet counts. 1, 2

Intravenous Immunoglobulin (IVIg)

IVIg is appropriate when: 1, 2

• Corticosteroids are ineffective or cause significant side effects 1
• More rapid platelet increase is required 1
• First-line treatment in the third trimester for counts <10,000/μL or counts 10,000-30,000/μL with bleeding 2

Second and Third Trimester Options

For non-splenectomized Rh(D)-positive patients, IV anti-D 50-75 μg/kg is effective and safe in the second and third trimesters, though augmentation with corticosteroids or IVIg is usually required to achieve target platelet count of 50,000/μL. 1

Refractory Cases

For patients failing first-line therapy: 1

• Combine first-line treatments in the weeks before delivery 1
• High-dose methylprednisolone (1000 mg) possibly combined with IVIg or azathioprine 1
• Azathioprine is safe during pregnancy based on SLE and renal transplantation data, though response is slow 1
• Cyclosporin A has not been associated with significant maternal or fetal toxicity 1

Splenectomy Considerations

Splenectomy is best performed in the second trimester if necessary, and may be performed laparoscopically, though technically difficult beyond 20 weeks' gestation. 1

Appropriate vaccination during or after pregnancy is required after splenectomy. 1

Management at Delivery

Mode of Delivery

The mode of delivery should be determined by obstetric indications alone, not by maternal platelet count—there is no evidence that cesarean section is safer for the thrombocytopenic fetus than uncomplicated vaginal delivery. 1, 2

Prophylactic Platelet Transfusions

Transfuse platelets before delivery when: 1, 2

• Maternal platelets <10,000/μL with planned cesarean section 1, 2
• Epistaxis or mucous membrane bleeding with expected vaginal delivery 1, 2

Anesthesia Considerations

Regional anesthesia requires careful risk-benefit analysis when platelet count drops below 50,000/μL, with multidisciplinary discussion. 1

For counts below 50,000/μL, spinal may be safer than epidural blockade due to smaller needle size and decreased risk of vascular damage. 1

Monitor the trend as well as absolute value—rapidly falling counts require closer observation than stable low counts. 1

Procedures to Avoid During Labor

Avoid fetal scalp electrodes, fetal blood samples, ventouse delivery, and rotational forceps due to increased fetal hemorrhagic risk. 1

Neonatal Management

Platelet Monitoring

Check cord blood platelet count at delivery by clean venepuncture of cord vessel, not by draining blood from cord. 1

Monitor neonatal platelet counts for 3-4 days after birth, as counts typically nadir at 24-48 hours (days 2-5) after delivery. 1, 2

Most hemorrhagic events in neonates occur 24-48 hours after delivery at the nadir of the platelet count, not during delivery itself. 1

Neonatal Treatment

Avoid intramuscular injections (including vitamin K) until platelet count is known. 1

IVIg 1 g/kg is recommended for neonatal platelets <20,000/μL without evidence of intracranial hemorrhage. 1, 2

Life-threatening hemorrhage requires platelet transfusion combined with IVIg. 1

Imaging and Follow-up

Perform transcranial ultrasonography on neonates with platelet counts <50,000/μL at delivery. 1

Consider brain imaging if platelet count at birth is <20,000/μL. 1

Neonatal thrombocytopenia secondary to maternal ITP may last for months and occasionally requires a second dose of IVIg at 4-6 weeks after birth. 1

Exclude neonatal alloimmune thrombocytopenia by laboratory testing when severe neonatal thrombocytopenia and hemorrhage are present. 1

Critical Prognostic Information

The neonatal mortality rate for babies born to mothers with ITP is less than 1%, with intracranial hemorrhage occurring in only 0-1.5% of thrombocytopenic infants. 1

Fetal or neonatal platelet count cannot be reliably predicted by maternal platelet count, platelet antibody levels, or history of maternal splenectomy. 1

In ITP, the second fetus is usually as affected as the first (unlike alloimmune thrombocytopenia where fetal thrombocytopenia tends to worsen in subsequent pregnancies). 1

Special Considerations

Despite thrombocytopenia, ITP in pregnancy may be associated with a prothrombotic state due to anticardiolipin antibody syndromes or other pregnancy-related factors, and VTE prophylaxis should be considered. 1

Women with ITP should not be discouraged from pregnancy if platelet counts are >50,000/μL, but should be counseled against pregnancy if counts remain <10,000/μL after splenectomy and other treatments. 2

Prenatal care should involve or be managed by an obstetrician specializing in high-risk pregnancies. 2