Venous thromboembolism (VTE) in obstetrics Dr.Roaa H. Gadeer MD

Objectives Incidence Pathogenesis Predisposing factors Clinical Presentations Prophylaxis Management choices Antepartum Postpartum

Incidence Deep venous thrombosis High recurrent risk: 7-13% antepartum: 0.5-3 per 1000 pregnancies postpartum: 0.5-18 per 1000 pregnancies High recurrent risk: 7-13% pulmonary embolus untreated DVT: 24% have PE, 15% mortality treated DVT: 5% have PE, 1-2% mortality

Number of pregnancy deaths from 1982-1992 in Canada

Pathogenesis of VTE in pregnancy Stasis Hypercoagulation Vessel wall abnormality

Predisposing factors associated with pregnancy

Major risk factors immobility before the operation >4 days previous hx of DVT/PE: 7-13% risk of recurrence thrombophilias trauma or infection age > 35 obesity long hospitalization dehydration/shock immobility before the operation >4 days chemotherapy

Thrombophilias Congenital: resistance to activated protein C (factor V leiden) hyperhomocysteinemia (controversial) protein S, C deficiency: 2-4% risk, 18-20% risk during postpartum antithrombin III deficiency: 25-55% risk Prothrombin G20210A

Thrombophilias Acquired: antiphospholipid syndrome (APLS): role to cause VTE is uncertain

Prevalence in population General population Thrombosis Factor V leiden 5-9% 20-40% Prothrombin G20210A 3% 6-15% Protein C def 0.3% 1-2% Protein S 0.2% ATIII def 0.07% <1% Hyperhomocystin-emia 5% 5-10%

Clinical Presentations Superficial venous thrombosis Typically associated with superficial varicosities and IV catheterization DX and management similar to non-pregnant women

Clinical Presentations 2. DVT Presentations largely depends on the degree of occlusion Lt>Rt (80%) Early puerperium (why?) c/s or malpositioning in the leg holder

Clinical Presentations Symptoms of DVT calf pain, tenderness, swelling, cord, + Homan’s sign discoloration 50% thought to have DVT have negative U/S

Clinical Presentations 3. PE Leading cause of perinatal maternal loss in developed countries Declining incidence

Symptoms of PE and DVT Symptoms of PE: tachypnea 80% dyspnea 81% pleuritic pain 72% apprehension 60% cough 54% tachycardia 43% T > 37.5C 35%* in those with proven PE

Investigations for PE: CXR nondiagnostic, excludes other causes of hypoxemia ABG’s A-a gradient, maybe normal in >20% Doppler & US Ventilation/perfusion Lung (V/Q) scan 0.2 rads to fetus 95% correlation with venography Spiral CT (non invasive)

Investigations for PE: contrast venography, gold standard, 0.25 rads to fetus for legs pulmonary angiography, gold standard, 0.25 rads to fetus, 1% maternal morbidity, 1/2000 mortality

Diagnosis Use US plus V/Q scan No known human effects for fetal exposure < 5 rads If therapy will be altered by an invasive diagnostic procedure, the benefit far overweighs the risk to mother and fetus given 15-40% mortality for untreated PE

PE Prevalence Reports suggest equal distribution between antenatal and postnatal period Higher mortality in the post partum period Can be asymptomatic DVT until embloization develop

Recommendations for thromboprophylaxis Antepartum all pregnant women who had previous VTE should be tested for thrombophilia factors; for single episode of prior VTE with transient risk factors: surveillance (1C) for single episode of idiopathic VTE: surveillance or UFH or prophylactic LMWH dose (1C) for single episode of VTE and thrombophilia (except protein S): surveillance (except decreased antithrombin) or UFH or prophylactic LMWH dose (1C)

Antepartum continues: known thrombophilia: surveillance (except decreased antithrombin) or UFH or prophylactic LMWH dose (1C) recurrent episodes of VTE: adjusted dose of UFH or adjusted dose of LMWH (1C) > 3 moderate risk factors: surveillance or UFH or prophylactic LMWH dose (1C)

Recommendations for thromboprophylaxis Postpartum Warfarin should be offered to all postpartum women who had previous VTE (1C)

Low molecular weight heparin Adjusted dose LMWH: enoxaparin 1 mg/kg sc q12h, dalteparin 200 IU/kg sc q24h Advantages: possibly less risk of thrombocytopenia osteoporosis more predictable therapeutic effect OD or BID administration monitor anti-Xa levels in third trimester

Low molecular weight heparin Disadvantages: more difficult to reverse drug cost higher but no need for hospitalization

IV Heparin Advantages: inhibits thrombin by activating AT-III, prevents conversion of fibrinogen to fibrin need baseline CBC, INR PTT initial 5000 IU bolus, then 1000-1500 IU/hr, INR & PTT q6hr PTT therapeutic level 1.5-2.5, then INR/PTT q24h Advantages: doesn’t cross placenta not excreted in breast milk

IV Heparin Disadvantages: rapidly reversible (protamine sulfate 1mg/100units) no increase in perinatal mortality or morbidity over control Disadvantages: bleeding in 4-8% osteoporosis (15,000U/d > 5 months) thrombocytopenia (by day 4) Cost and compliance

Warfarin easily crosses placenta up to 70% fetal complications if in 1st trimester IUGR, chondrodysplasia punctata multiple congenital anomalies 20-30% complication rate in 2nd-3rd trimester Long half life

Management during peripartum Therapy throughout pregnancy and 8-12 weeks post partum IV Heparin and LMWH should be held once labor is established in order to use local anesthesia If therapeutic PTT is required in labor, patient should be switched to IV heparin Therapeutic PTT may increase the incidence of hematomas but not PPH

Management during peripartum Avoid trauma or C/S at delivery midline episiotomy if necessary avoid tears Resume heparin 6 hrs postpartum Start Warfarin when oral intake tolerated Avoid OCP, estrogen Consult!

Take home message Thromboprophylaxis is recommended for previous VTE hx and a known thrombophilia; idiopathic VTE, recurrent VTE, and more than 3 major risk factors for VTE (II B) Diagnosis of VTE is clinical suspicion + lab tests, never hesitate to order V/Q scan spiral CT or angiography if the result will change management Treatment is long term: till postpartum 8-12 weeks. Considering side effects of different drugs, cost, local anesthesia, avoiding instrument delivery

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