venous thromboembolism (vte) in obstetrics dr.roaa h. gadeer md
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Venous thromboembolism (VTE) Venous thromboembolism (VTE) in obstetricsin obstetrics
Dr.Roaa H. GadeerMD
ObjectivesObjectives
IncidencePathogenesisPredisposing factorsClinical PresentationsProphylaxisManagement choices
– Antepartum– Postpartum
IncidenceIncidence
Deep venous thrombosis– 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
0
2
4
6
8
10
12
14 PE
postpartumhemorrhage
amniotic fluidemboli
preeclampsia
anesthetics
ectopicpregnancy
septicemia
undetermined
Pathogenesis of VTE in pregnancyPathogenesis of VTE in pregnancy
Stasis Hypercoagulation
Vessel wall abnormality
Predisposing factors associated Predisposing factors associated with pregnancywith pregnancy
Hypercoagulability Stasis Endothelial damage
Increased factors: II, V, VII, VIII, IX, X, XII, fibrinogen
Increased venous distensibility and decreased tone
Vascular damage at delivery (CS or operative vaginal deliveries)
Increased platelet aggregation 50% decrease in venous flow in lower extremity by 3rd trimester
Decreased protein S, tissue plasminogen activator, factor XI, XIII
Uterus is mechanical impediment to venous return
Increased resistance to activated protein C
Decreased or normal antithrombin
Major risk factorsMajor risk factors 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 dayschemotherapy
ThrombophiliasThrombophilias
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
ThrombophiliasThrombophilias
Acquired:– antiphospholipid syndrome (APLS): role
to cause VTE is uncertain
Prevalence in population 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% 1-2%
ATIII def 0.07% <1%
Hyperhomocystin-emia
5% 5-10%
Clinical PresentationsClinical Presentations
1. Superficial venous thrombosis Typically associated with
superficial varicosities and IV catheterization
DX and management similar to non-pregnant women
Clinical PresentationsClinical Presentations
2. DVT Presentations largely depends on
the degree of occlusion Lt>Rt (80%) Early puerperium (why?)
Symptoms of DVT– calf pain, tenderness, swelling,
cord, + Homan’s sign– discoloration– 50% thought to have DVT have
negative U/S
Clinical PresentationsClinical Presentations
Clinical PresentationsClinical Presentations
3. PE Leading cause of perinatal
maternal loss in developed countries
Declining incidence
Symptoms of PE and DVTSymptoms 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: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)
– 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
Investigations for PE:Investigations for PE:
DiagnosisDiagnosis
Use US plus V/Q scanNo known human effects for fetal
exposure < 5 radsIf 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 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 Recommendations for thromboprophylaxisthromboprophylaxis 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: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)
PostpartumWarfarin should be offered to all
postpartum women who had previous VTE (1C)
Recommendations for Recommendations for thromboprophylaxisthromboprophylaxis
Low molecular weight heparinLow 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
Disadvantages:
more difficult to reverse
drug cost higher but no need for hospitalization
Low molecular weight heparinLow molecular weight heparin
IV HeparinIV Heparin
– 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 HeparinIV Heparin
– 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 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 peripartumManagement 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
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!
Management during peripartumManagement during peripartum
Take home messageTake 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