Thrombocytopenia in pregnancy
From IDWiki
Background
Definition
- Low platelet count in pregnancy, generally considered to be less than 100
Pathophysiology
- Most commonly, thrombocytopenia of pregnancy is caused by dilution from increased plasma volume, similar to anemia in pregnancy, and is usually more noticeable in T2 and T3
Etiology
- Gestational thrombocytopenia of pregnancy (70%)
- Hypertensive disorders (20%)
- Immune disorders (5%)
- Other (5%)
Epidemiology
- About 10% of pregnant women have platelets less than 150
Clinical Manifestations
Disease | % | Diagnostic Features | Lab Findings | Clinical Features | Pathophys | Comments |
---|---|---|---|---|---|---|
Gestational thrombocytopenia | 5-9 | Onset 2nd-3rd trimester. Normal PLT previously. No neonatal thrombocytopenia. | Plt >70 | Typically normal | Unclear | Diagnosis of exclusion. Resolves postpartum. No fetal thrombocytopenia. |
ITP | <1 | Onset any trimester. May see thrombocytopenia outside pregnancy. | Plt <100 +/- large platelets | May have bleeding, bruising, petechiae | Antibody-mediated peripheral plt destruction with decrease thrombopoiesis. | Diagnosis of exclusion. May be associated with fetal thrombocytopenia. |
Preeclampsia | 5-8 | Onset late 2nd or 3rd trimester (>20 weeks). | Proteinuria >0.3 g/d | BP ≥140/90 | Systemic endothelial dysfunction. Inadequate placentation. | May precede other manifestations of preeclampsia. Can present postpartum. |
HELLP | <1 | 70% late 2nd or 3rd trimester, 30% postpartum. | MAHA, high liver enzymes, high LDH. | Signs of preeclampsia, but may be normotensive without proteinuria. | Same as preeclampsia. | Variant of preeclampsia. |
AFLP | <0.01 | Onset in 3rd trimester. | Plt >50. High liver panel, creat, WBC, urate, ammonia. High PT/PTT, decreased fibrinogen. Hypoglycemia. | RUQ pain. Jaundice, nausea/vomiting. Hepatic encephalopathy. | Preeclampsia spectrum. | MAHA not characteristic. Conjugated bili often high. Liver dysfunction greater than HELLP/preeclampsia. |
TTP/aHUS | <0.01 | Onset any trimester, but more common during 3rd or postpartum. | MAHA, elevated creatinine, schostocytes on blood film. | Fever, abdo pain, n/v, headache, vis changes, altered mental status. | Congenital deficiency of ADAMTS13 (TTP) or complement dysregulation (aHUS). | ADAMTS13 activity <5% in TTP. Liver panel and BP usually normal. |
Investigations
- CBC and blood film
- Look for bicytopenia concerning for thrombotic microangiopathy
- Platelets <70 more consistent with ITP than gestational thrombocytopenia
- For ITP
- HIV, HBV, HCV
- Liver and thyroid tests
- Immunoglobulin levels
- DAT
- APLA and ANA
- Platelet antibody testing is useless
Management
- Depends on etiology
- Gestational thrombocytopenia
- No specific management
- ITP
- No need to treat until 36 weeks if platelets over 30
- If platelets < 30 or bleeding
- Prednisone (0.25-1 mg/kg) or IVIg (1 g/kg ideally body weight, max 60mg)
- Monitor newborn for post-partum thrombocytopenia
Prognosis
- In ITP, 25% of neonates will have thrombocytopenia and 10% will need treatment