VTE and Pregnancy
Huma Khan MDMCH fellow
August 3rd, 2011
objectivesEpidemiology of VTE in pregnancy
to be able to identify the causes of vte
To understand and identify the different diagnostic tools
Understand prenatal management
To be aware of the different pharmacotherapies
Identify risk factors for post natal management
Case 1AK is a 24 yr old obese AA G2P0010, who comes for an initial prenatal visit. She is very sure of her lmp which places her at about 8wk 3d GA. She states this a planned pregnancy and that she has been taking pnv’s.
Pmhx: DVT in her left leg 4yrs ago,
Pshx: none
Meds: pnv
Case 1
Fhx: DM, cHTN
Shx: married, employed, no smoking, no etoh, hx of thc in college with occasional addition of other substances which she denies using once she graduated
Obhx: SAB 2 yrs ago at 6 wks different partner
epidemiology
VTE( DVT & PE) occurs in 5 -12 per 10,000 pregnanciesPostpartum 3 -7 per 10,000 deliveries7-10 fold increase in antepartum15- 35 fold in post partumPE leading cause of death in developing countries current deaths from PE: 1.1 -1.5 per 100,000 deliveries
anatomy
virchow’s triadVenous stasis
hypercoagulability
Vascular damage
pathophysiology Virchow's triad
Venous stasis:
1st trimester to 36wk Progesterone induced venodilation Right iliac artery over left iliac vein Gravid uterus Immobilization
pathophysiology Virchow's triad
Vascular damage: Compression at delivery Assisted or operative delivery
Hypercoagulability: procoagulant factors anticoagulant activity fibrinolytic activity = more thrombin generation + less clot dissolution
Other risk factors black raceHeart diseaseSickle cell diseaseDiabetesLupus
SmokingMultiple pregnancyAmaObesity ( BMI > 30)C-section( especially emergent or after long labor)
Thrombophilic disorders disorder of hemostasis predisposing to thrombotic event
Inherited Factor V Leiden Prothrombin G20210A
Acquired Antiphospholipid antibody syndrome Lupus anticoagulant
Thrombophilic disorders cause 50 % of VTE in pregnancy Occur only in 0.1% of pregnancies
Universal screening not cost effective
Screening affected in pregnancy protein S levels fall in 2nd trimester Massive thrombus & nephrotic syndrome decrease
antithrombin levels Liver disease decrease protein C & S levels
Screening should be done after pregnancy and when no longer taking anticoagulants
Thrombophilic disorders
Complications
Early and late losses IUGR Placental abruption
Presentation of vteDifficult to differentiate from pregnancy sx’s
DVT: Unilateral leg pain and swelling, especially left leg ≥ 2 cm calf circumference difference 1st trimester Homan’s sign
Diagnosis tree
Dresand et al. aafp,77:1709-16, 2008
Diagnostic tools for DTVVCUS ( venous compression ultrasonagraphy)
Sensitivity : 89 - 97% Specificity : 94 - 99% Less accurate for isolated calf and iliac vein thrombosis
D-Dimer Levels increase during pregnancy Usually positive and hence of little use Negative test with low clinical probability has a NPV of 99.5 %
when highly sensitive assay used. positive test sensitivity is 100% & specificity is 60% hence
additional testing is needed
MRI and ct can be done in high probability pts
presentationDifficult to differentiate from pregnancy sx’s
PE: Dyspnea Chest pain Unexplained tachycardia
PE diagnosis tree
Dresand et al. aafp,77:1709-16, 2008
Diagnostic tools for PEv/q scan
PPV when combined with high clinical pretest is 96% Only 56% with low clinical pretest Radiation dose : 0.003 -.077 mGY
ct In one study PPV’s in
Lobar: 97% segmental:68% Subsegmental: 25%
False positive rates: 30% , detected incorrectly in segmental/ subsegmental
Radiation dose: 0.02 -0.06 gy
Case 1AK is a 24 yr old obese AA G2P0010, who comes for an initial prenatal visit. She is very sure of her lmp which places her at about 8wk 3d GA. She states this a planned pregnancy and that she has been taking pnv’s. Pmhx: DVT in her left leg 4yrs ago, Pshx: noneFhx: DM, cHTNMeds: pnvShx: married, employed, no smoking, no etoh, hx of thc in college with occasional addition of other substances which she denies using once she graduatedObhx: SAB 2 yrs ago at 6 wks different partner
Case 1 : extra stuffOn further examination you find
BP: 140/85BMI of 32A few varicose veins on her right calfOn US she is 10wk with twin gestation
Case 1 managementIdentify the risk factors
prenatal management
What do do during labor and delivery
Identify risk factor for post partum management
Rcog Green- top guideline 37, 2009
management prophylaxis in pregnancy
Marik & Plante nejm,359:2025-33, 2008
Therapeutic dosing in pregnancy
Vena caval filters
Marik & Plante nejm,359:2025-33, 2008
Which heparin???LMWH
More predictable dose responseMore dose independent mechanisms of clearanceLong plasma half lifeOnce or twice daily dosingNo lab visitsLower risk of bleeding, HIT & fracturesNot easily reversed
UFHDose dependent responseClearance is dependent on renal / liver functionHalf life is short and dose dependentMultiple dosingLabs for PLTSHigh risk of bleeding and HITEasily reversed by protamine sulphate
Why not Warfarin ?!Crosses placentaIncreases miscarriage, stillbirth, embryopathy (midface hypoplasia,stippled epiphyses) if exposed in 1st trimesterIn 2nd and 3rd trimester causes CNS abnormalities and hemorrhage
It is compatible with breast feeding
During labor and deliverySwitch to UFH several wks before
stop all anticoagulation with onset of labor
If planned IOL or c-section then stop 24 hrs prior to
Management varies based on prophylaxis /treatment doses
Anticoagulation & Anesthesia neuroaxial anesthesia contra-indicated in spontaneous labor with full anticoagulation
Spinal anesthesia placed 12 hrs after prophylactic dose of LMWH 24 hrs after therapeutic dose of LMWH 6 hrs after UFH dose and confirmed normal activated partial-
thromboplastin time
General preferred if emergent c-section Anticipate larger blood loss
reversal of UFH and LMWH
Bourjeily et al. lancet 375:500-12, 2010
After birthPost partum thromboprophylaxis not routinely indicatedASA not usedThromboprophylaxis for 6-12 wksWarfarin can be used
Post OPIncidence of PE higher by a factor of 2.5 to 20Incidence of fatal PE by a factor of 10
Thromboprophylaxis highly effective in reducing the high incidence
Duration is 3-7 days for intermediate riskUp to 6 wks for high risk.
Rcog Green- top guideline 37, 2009
Thank you