Huma Khan MD
MCH fellow
August 3rd, 2011
Epidemiology 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
AK 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
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
 VTE( DVT & PE) occurs in 5 -12 per 10,000
pregnancies
Postpartum 3 -7 per 10,000 deliveries
7-10 fold increase in antepartum
15- 35 fold in post partum
PE leading cause of death in developing
countries
 current deaths from PE: 1.1 -1.5 per 100,000
deliveries
Venous stasis
Vascular
damage
hypercoagulabil
ity
 Virchow's triad
 Venous stasis:





1st trimester to 36wk
Progesterone induced venodilation
Right iliac artery over left iliac vein
Gravid uterus
Immobilization
 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

 black race
Smoking
Heart disease
Multiple pregnancy
Sickle cell disease
Ama
Diabetes
Obesity ( BMI > 30)
Lupus
C-section( especially
emergent or after
long labor)
 disorder of hemostasis predisposing to
thrombotic event
 Inherited


Factor V Leiden
Prothrombin G20210A
 Acquired


Antiphospholipid antibody syndrome
Lupus anticoagulant
 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
Complications
 Early and late losses
 IUGR
 Placental abruption
Difficult 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

Dresand et al. aafp,77:1709-16, 2008
VCUS ( 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
Difficult to differentiate from pregnancy sx’s
PE:
 Dyspnea
 Chest pain
 Unexplained tachycardia
Dresand et al. aafp,77:1709-16, 2008
v/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
AK 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
Fhx: DM, cHTN
Meds: pnv
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
On further examination you find
 BP: 140/85
 BMI of 32
 A few varicose veins on her right calf
 On US she is 10wk with twin gestation
Identify 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
 prophylaxis in pregnancy
Marik & Plante nejm,359:2025-33, 2008
Therapeutic dosing in pregnancy
Vena caval filters
Marik & Plante nejm,359:2025-33, 2008
LMWH
UFH
 More predictable dose
 Dose dependent response
response
 More dose independent
mechanisms of clearance
 Long plasma half life
 Once or twice daily
dosing
 No lab visits
 Lower risk of bleeding,
HIT & fractures
 Not easily reversed
 Clearance is dependent
on renal / liver function
 Half life is short and
dose dependent
 Multiple dosing
 Labs for PLTS
 High risk of bleeding and
HIT
 Easily reversed by
protamine sulphate
Crosses placenta
Increases miscarriage, stillbirth, embryopathy
(midface hypoplasia,stippled epiphyses) if exposed
in 1st trimester
In 2nd and 3rd trimester causes CNS
abnormalities and hemorrhage
It is compatible with breast feeding
Switch 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
 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
Bourjeily et al. lancet 375:500-12, 2010
Post partum thromboprophylaxis not routinely
indicated
ASA not used
Thromboprophylaxis for 6-12 wks
Warfarin can be used
Incidence of PE higher by a factor of 2.5 to 20
Incidence of fatal PE by a factor of 10
Thromboprophylaxis highly effective in
reducing the high incidence
Duration is 3-7 days for intermediate risk
Up to 6 wks for high risk.
Rcog Green- top guideline 37, 2009