Obstetric Topic 15. Pregnancy and hematologic disorders

I. Anemia in Pregnancy

General

• Anemia: common in pregnancy, especially 3rd trimester.
• Symptoms: fatigue, pallor, dizziness, dyspnea, tachycardia; severe cases → angina/HF risk.
• Risks: preterm birth, low birth weight, postpartum infection, poor maternal reserve during bleeding.
• Diagnosis: CBC + MCV + ferritin/B12/folate as indicated.
• Severe symptomatic anemia: consider transfusion.

Iron-Deficiency Anemia

• Cause: ↑ iron demand + poor intake/absorption + low stores.
• Features: microcytic hypochromic anemia, ↓ ferritin.
• Treatment: oral iron first-line; IV iron if severe, late pregnancy, intolerance or poor absorption.
• Prevention: routine elemental iron about 30-60 mg/day in many prenatal protocols.

Folate-Deficiency Anemia

• Cause: ↑ folate demand + poor intake/malabsorption.
• Features: macrocytic/megaloblastic anemia.
• Fetal risk: neural tube defects.
• Prevention: folic acid 400 micrograms/day; previous NTD pregnancy → 4 mg/day preconception through 1st trimester.
• Treatment of deficiency: folic acid, often 1 mg/day or higher by protocol.

Sickle Cell Disease

• Cause: autosomal recessive beta-globin mutation → HbS.
• Pregnancy: anemia and vaso-occlusive crises may worsen.
• Maternal risks: infection, preeclampsia/HT, VTE, acute chest syndrome.
• Fetal risks: IUGR, preterm birth, low birth weight, stillbirth.
• Management: high-risk care, folic acid, hydration, treat infections/pain crises, thromboprophylaxis when indicated.
• Avoid hydroxyurea in pregnancy unless specialist exception; offer hemoglobinopathy testing/genetic counseling.

II. Thrombocytopenia and DIC

Thrombocytopenia

• Definition: platelet count <150,000/microL.
• Gestational thrombocytopenia: common, mild, late pregnancy, usually >70,000/microL, no bleeding → no treatment.
• Preeclampsia/HELLP: thrombocytopenia + hypertension/organ dysfunction → stabilize mother and deliver according to severity/gestational age.
• Other causes: immune thrombocytopenia, DIC, TTP, HUS, SLE/APS, drugs.
• Red flags: platelet count <70,000, early pregnancy onset, bleeding, hemolysis, renal/CNS symptoms → urgent evaluation.

DIC

• Pregnancy causes: placental abruption, amniotic fluid embolism, HELLP, sepsis, retained dead fetus, massive hemorrhage.
• Features: bleeding/bruising + low platelets + low fibrinogen + prolonged PT/aPTT + high D-dimer.
• Treatment: treat cause + blood components as needed: RBC, platelets, FFP, cryoprecipitate/fibrinogen.

III. Thromboembolism

Why Pregnancy Is Hypercoagulable

• Virchow triad:

1. Stasis: gravid uterus compresses pelvic/lower limb veins.
2. Endothelial injury: delivery/uteroplacental vessel injury.
3. Hypercoagulability: ↑ fibrinogen and clotting factors.

• Risk is highest postpartum, especially after cesarean.
• Thrombophilia: inherited Factor V Leiden, prothrombin mutation, protein C/S or antithrombin deficiency; acquired APS.
• Complications: DVT, PE, pregnancy loss/placental complications in APS.

DVT / PE

• DVT symptoms: unilateral leg swelling/pain, calf difference, tenderness; often left-sided.
• PE symptoms: dyspnea, chest pain, tachycardia, hypoxia, syncope.
• DVT diagnosis: compression ultrasound first-line.
• PE diagnosis: imaging if suspected; do not rely on D-dimer alone.
• Treatment: therapeutic LMWH through pregnancy and at least 6 weeks postpartum, with minimum total 3 months.
• Avoid in pregnancy: warfarin for most indications, direct oral anticoagulants.
• Previous VTE/high-risk thrombophilia: consider prophylactic LMWH during pregnancy and postpartum.