This document discusses deep vein thrombosis and pulmonary embolism in pregnancy. It covers the pathogenesis, risk factors, diagnosis, treatment, and prevention of these conditions. The main points are: 1. Pregnancy increases the risk of venous thromboembolism due to venous stasis, endothelial injury, and a hypercoagulable state. Common risk factors include cesarean section, prematurity, and inherited or acquired thrombophilia. 2. Diagnosis involves Doppler ultrasound, MRI, or CT imaging depending on the suspected location of the clot. Treatment involves anticoagulants like low molecular weight heparin or unfractionated heparin. 3. Thromb

1. Deep vein thrombosis and
pulmonary embolism in
pregnancy
Military Maternity Hospital
28 September 2015
D.Kahtan Sbeqi

2. INTRODUCTION
 Pregnancy and the puerperium are well-
established risk factors for venous
thromboembolism (VTE)
 incidence of VTE ranging from 4 to 50
times higher in pregnant versus non-
pregnant women
 it an absolute incidence rate of 1 in 500 to
2000 pregnancies (0.025 to 0.10 percent)
 more common postpartum than
antepartum
 DVT is far more common in the left than
the right leg

3. PATHOGENESIS AND RISK FACTORS
Virchow's triad :venous stasis, endothelial
injury, and a hypercoagulable state
Stasis :
 pregnancy-associated changes in venous
capacitance and compression of large
veins by the gravid uterus
Endothelial injury:
 Delivery is associated with vascular injury
and changes at the uteroplacental surface
 Forceps, vacuum extraction, or surgical
delivery can exaggerate vascular intimal
injury

4. Hypercoagulability:
 associated with progressive increases in
several coagulation factors, such as
factors I, II, VII, VIII, IX, and X, along with
a decrease in protein S
 A progressive increase in resistance to
activated protein C
 Activity of the fibrinolytic inhibitors is
increased during pregnancy

5.  risk factors included cesarean section,
premature delivery, or history of cardiac
disease. Multiple births
 The risk of deep vein thrombosis (DVT) is
approximately twice as high after
cesarean delivery than vaginal birth
 In addition, DVT is far more common in
the left than the right leg
 increased venous stasis in the left leg
related to compression of the left iliac vein
by the right iliac artery, coupled with
compression of the inferior vena cava by
the gravid uterus itself

8. INHERITED THROMBOPHILIA
Common inherited hypercoagulable state
 Factor V Leiden mutation
 Prothrombin gene mutation
 Protein S deficiency
 Protein C deficiency
 Antithrombin deficiency
 Dysfibrinogenemia
ACQUIRED THROMBOPHILIA
 include a prior thrombotic event, recent
major surgery, presence of a central venous
catheter, trauma, immobilization, malignancy,
pregnancy, the use of oral contraceptives or
heparin, myeloproliferative disorders, and
antiphospholipid syndrome (APS)

9. DIAGNOSIS :
 Clinical examination
 Laboratory studies: D-dimer,low specificity, high
sensitivity
 Radiographic evaluation: Deep vein
thrombosis:
 Doppler ultrasound: less sensitive for calf vein
thrombosis (which is less common in the pregnant
population) and pelvic vein thrombosis
 Magnetic resonance imaging (MRI):The safety of
MRI during pregnancy has not been proven
 Ascending contrast venography:gold standard for
the diagnosis of lower extremity DV, gold
standard for the diagnosis of lower extremity
DVT:delivered radiation to the fetus is small (<500
mcGy)
 We recommend compression venous color
Doppler ultrasound as the initial test in pregnant
women with suspected DVT

10. Pulmonary embolism
 negative examinations for DVT are not definitive
because fewer than 30 percent of unselected patients
with PE have radiographic evidence of DVT at the
time of presentation
 CT angiography is the non-invasive study of choice
for the diagnosis of pulmonary embolism in the non-
pregnant population
 the chest X-ray (CXR) is normal, V/Q scanning is
more accurate
 Because of the superior accuracy of V/Q scanning
and lower maternal breast irradiation, there has been
a movement away from CT angiography toward V/Q
scanning as the diagnostic test of choice in the
workup of pulmonary embolism in pregnancy in
women with a negative CXR. In those patients with an
abnormal CXR, CT angiography remains the test of
choice.
 The estimated fetal radiation exposure from
the combination of a chest radiograph, V/Q
scanning, and pulmonary arteriography is less than

11. Deep vein thrombosis and
pulmonary embolism in
pregnancy:
treatment

12.  When there is a high clinical suspicion for
acute PE, empiric anticoagulant therapy is
indicated prior to the diagnostic
evaluation. Anticoagulant therapy is
discontinued if VTE is excluded
 When there is suspicion for DVT alone
(no clinical evidence or suspicion of acute
PE), anticoagulant therapy is generally
withheld until VTE is confirmed, assuming
that diagnostic evaluation can be
performed in a timely fashion

13.  SC LMWH is preferred over IV UFH or SC
UFH in most patients because it is easier
to use and it appears to be more
efficacious with a better safety profile.
 In contrast, IV UFH is preferred in patients
who have a markedly elevated risk of
bleeding or persistent hypotension due to
PE
 short half-life and near complete reversal
with protamine make it the most desirable
anticoagulant if it needs to be
discontinued due to bleeding or to perform
a procedure

14. Dosing
 LMWH :initial doses of SC LMWH include
dalteparin 200 units/kg once daily,
tinzaparin 175 units/kg once daily, or
enoxaparin 1 mg/kg every 12 hours
 The dose is then titrated to an anti-Xa
level of 0.6 to 1.0 IU/mL for twice daily
administration, or 1 to 2 IU/mL for once
daily administration

15.  IV UFH :Initial dosing of IV UFH consists
of an IV UFH bolus of 80 units/kg,
followed by a continuous infusion of 18
units/kg per hour
 The infusion is titrated every six hours to
achieve a therapeutic activated partial
thromboplastin time (aPTT)
 SC UFH — A reasonable initial dose of
SC UFH is 17,500 units every 12 hours

16. Labor and delivery
 Treatment with SC LMWH or SC UFH should
be discontinued 24 to 36 hours prior to
delivery if the delivery time is predictable
(induction of labor, planned cesarean
section)
 patients may benefit from having their SC
LMWH or SC UFH switched to IV UFH,
which can be discontinued 4 to 6 hours prior
to delivery
 Neuraxial anesthesia should not be
administered to an anticoagulated patient
 In cases in which preterm delivery is
anticipated (eg, triplets, preterm rupture of
membranes, significant cervical dilation,
preeclampsia, growth restriction), it is
common to discontinue SC LMWH or SC
UFH at 36 weeks of gestation. IV UFH is

17. After delivery
 A heparin regimen (SC LMWH, IV UFH, or
SC UFH) should be restarted 12 hours after
a cesarean delivery or 6 hours after a
vaginal birth
 If warfarin therapy is chosen, the patient
should receive both warfarin and heparin
for at least five days
 The heparin should not be stopped until the
(INR) has been within therapeutic range
(usually 2 to 3) for two consecutive days
 Length of therapy — Anticoagulant therapy
generally continues for at least six weeks
postpartum
 a total duration of anticoagulant therapy of
at least six months for women whose only
risk factors for VTE were transient (eg,

18. Deep vein thrombosis and
pulmonary embolism in
pregnancy: Prevention

19.  Thromboprophylaxis can be
pharmacologic (ie, anticoagulation) or
mechanical (eg, graduated compression
stockings)
 The indications for thromboprophylaxis
differ for antepartum and postpartum
women
Antepartum :The 2008 American College of
Chest Physicians (ACCP) guidelines
 Single prior episode of VTE plus a higher
risk thrombophilia
 Multiple prior episodes of VTE
 Antithrombin deficiency

20. In contrast, the benefits, risks, and burdens of
thromboprophylaxis should be carefully
weighed:
 Single prior episode of VTE that was related
to pregnancy or estrogen use (eg,
contraceptives)
 Single prior episode of idiopathic VTE
 Single prior episode of VTE in a patient with
thrombophilia that is not considered higher
risk
Higher risk thrombophilias :antithrombin
deficiency, persistent antiphospholipid
antibodies, compound heterozygosity for the
prothrombin and factor V Leiden mutations,

21. Postpartum :There is generally a lower
threshold for initiating thromboprophylaxis
during the postpartum period, compared
with during pregnancy
 Postpartum thromboprophylaxis is
indicated for women who have had one or
more episodes of VTE
 who have any type of thrombophilia, even
those that are not considered higher risk
Cesarean section :thromboprophylaxis is
NOT recommended for women whose only
risk factors for VTE are the pregnancy and
CS

22. Thromboprophylaxis may be warranted for
women who have risk factors for VTE in
addition to the pregnancy and CS
 The ACCP guidelines for VTE and
pregnancy suggest the following for women
who have undergone cesarean section
 Women who have only one additional risk
factor for VTE should receive either
thromboprophylaxis, graduated compression
stockings, or a pneumatic compression
device while in the hospital following delivery
 Women who have multiple additional risk
factors for VTE should receive
thromboprophylaxis plus graduated
compression stockings and/or pneumatic
compression devices while in the hospital
following delivery

23.  REGIMENS
 Low molecular weight heparin
 include dalteparin 5000 units once daily,
dalteparin 5000 units every 12 hours,
tinzaparin 4500 units once daily,
enoxaparin 40 mg once daily, or
enoxaparin 40 mg every 12 hours.
 Unfractionated heparin
 Fixed dose: SC UFH 5000 units every 12
hours
 Warfarin :It should be initiated at the same
time or after heparin is started because
warfarin alone is associated with an
increased incidence of VTE

24. Choosing a regimen
 LMWH-based regimens are generally
preferred for antepartum
thromboprophylaxis for several reasons
 LMWH is effective and safe in pregnant
women
DURATION :Antepartum
thromboprophylaxis should be continued
through the pregnancy
 It is generally discontinued 24 to 36 hours
prior to delivery
 The optimal duration of postpartum
thromboprophylaxis is uncertain. Several
clinical practice guidelines suggest four to