Deep Vein Thrombosis is an important and frequently missed out diagnosis that can often lead to sudden death in post operative patients. Did this powerpoint for an O&G seminar. Mainly focusses on DVT in OBG and its management and prevention. Kindly leave a comment and let me know what you think.

1. DVT PROPHYLAXIS
Dr. Ranjith R Thampi
CRRI
Department of Obstetrics and Gynaecology

2. Background
It is a common, yet preventable perioperative
complication.
Highest risk in critical care and spinal cord
injury patients- 60-80%
Post- Ortho Procedures: 40-60%
Post-General Surgery/ Obstetric- 15-40%
Variable for Urologic Cases

3. Incidence
• Incidence of Thrombophlebitis in Antepartum
period is 2/1000 pregnancies; of which,
Majority(Superficial) is 1.7/1000 pregnancies and
DVT is 3.6/1000 pregnancies
• In Postpartum period, incidence of superficial
thrombophlebitis increases by 7 times(12/1000)
and that of DVT by 4-5 times(15/1000)
• Thromboembolic complications in pregnancy
occur in 2-5/1000 deliveries, where clinical
presentation of DVT is found in 0.5-0.7% and PE
is found in 0.3%-1.2%.

4. Sites for DVT
 Ileo-femoral veins
(80% cases)
 Popliteal veins
 Calf veins(extending
proximally in 30%
cases)
 Inferior Vena
Cava(rarely)

5. Pathogenesis
• Physiologic changes during pregnancy
predispose to DVT with a 6-fold increase from
non-pregnant state, due to Virchow’s triad, i.e.,
- Venous Stasis
- Altered Blood Coagulability
- Vascular damage
*Infection
All concert together in promoting DVT in low flow
areas.

7. Risk Factors

8. Risk Factors

9. THE
COAGULATION
CASCADE

10. Coagulation mechanism

11. INTRINSIC
PATHWAY
XIIa XII
XIa XI
IXa IX
VIIIa VIII
X Xa
Va V
PROTHROMBIN THROMBIN
FIBRINOGEN FIBRIN

12. EXTRINSIC
PATHWAY
XIIa XII
Tissue Factor XIa XI
from damaged
endothelium VIIa VII
IXa IX
VIIIa VIII
X Xa
Va V
PROTHROMBIN THROMBI
N
FIBRINOGEN FIBRIN

13. Anticoagulants and
Thrombolytics
XIIa XII
Tissue Factor XIa XI
from damaged
endothelium VIIa VII
IXa IX
VIIIa VIII
X Xa
Va V
PROTHROMBIN THROMBIN
FIBRINOGEN FIBRIN Degradation
PLASMINOGEN Plasmin

14. FACT(Researched)
– Type A blood is associated with lower levels of
antithrombin III and higher levels of factor VIII than
type O blood.
– Women of reproductive age with type A blood are 4
times as likely to develop DVT.
– This association of risk with blood type A does not
extend to older men or to women past reproductive
age

16. Clinical Features
• Tenderness occurs in 75% confined to the calf muscles or
over the course of the deep veins in the thigh.
• Warmth or erythema of skin can be present over the area of
thrombosis.
• Clinical signs and symptoms of pulmonary embolism as the
primary manifestation occur in 10% of patients with confirmed
DVT.
• The pain and tenderness associated with DVT does not
usually correlate with the size, location, or extent of the
thrombus

17. Clinical Features
• Many patients are asymptomatic
• Pedal Edema, principally unilateral, is the
most specific symptom
• Leg pain (50%, )
• Pain can occur on dorsiflexion of the foot
(Homans sign).

18. Signs of DVT
• Tenderness
• Warmth or erythema of skin Can be present
• Clinical signs and symptoms of pulmonary
embolism as the primary manifestation occur in
10% of patients with confirmed DVT
• Moses’ sign- tenderness elicited by squeezing or
pressing firmly on sole of foot or calf

19. Phlegmasia cerulea dolens
Patients may have variable discoloration
of the lower extremity.
The most common abnormal hue is
reddish purple from venous
engorgement and obstruction.
In rare cases, the leg is cyanotic from
massive ileofemoral venous
obstruction. This ischemic form of
venous occlusion was originally
described as phlegmasia cerulea
dolens or painful blue inflammation.

20. The leg is usually markedly edematous, painful, and cyanotic.
Petechiae are often present

21. Differential Diagnosis
• Abcesses
• Baker’s cyst
• Cellulitis
• Musculoskeletal Injury
• Venous stasis

22. INVESTIGATIONS
• D-dimer
• Contrast Venography
• Duplex ultrasonography
• Impedance plethysmography
• MRI
• Nuclear Medicine Imaging Studies

23. D-dimer
Recent interest has focussed on the use of
D-dimer in the diagnostic approach to Deep
Vein Thrombosis
D-dimer has high sensitivity but low specificity
D-Dimer levels remain elevated in DVT for
about 7 days.

24. Venous Thromboembolism suspected

25. Contrast Venography
For many reasons, including allergic
reactions, contrast-induced Deep Vein
Thrombosis noninvasive studies have
essentially replaced venography as the
initial diagnostic test of choice.

26. Duplex ultrasonography
Sensitivity of duplex ultrasonography for
proximal vein Deep Vein Thrombosis is
97% but only 73% for calf vein Deep Vein
Thrombosis.

27. Impedance Plethysmography
Plethysmography is derived from the
Greek word meaning "to increase."
This procedure is based on recording
changes in blood volume of an extremity,
which are directly related to venous
outflow.

28. MRI
• MRI is the diagnostic test of choice for suspected
iliac vein or inferior vena caval thrombosis.
• In suspected calf vein thrombosis, MRI is more
sensitive than any other noninvasive study.
Nuclear Imaging
Nuclear medicine studies with I125-labeled fibrinogen are
not recommended now. Radioactive isotope
incorporates into a growing thrombus, this test can
distinguish new clot from an old clot

29. Management: All Patients
• Avoid dehydration unless there is a specific clinical
reason.
• Encourage early mobilisation.
• Aspirin or antiplatelet agents should not be considered
adequate prophylaxis.
• Consider temporary IVC filters for patients at a very high
risk of VTE (eg active malignancy or previous VTE
event) if there are contra-indications to pharmacological
and mechanical prophylaxis. These are devices which
can be inserted into the inferior vena cava to prevent the
development of a pulmonary embolus.

30. Choice of prophylaxis:
Mechanical
Several methods are available:
•Graduated compression stockings are effective in decreasing the risk of DVT,
either alone or in combination with pharmacological prophylaxis in high-risk
patients. Thigh-length graduated compression/anti-embolism stockings can be
used unless contra-indicated (eg in patients with established peripheral arterial
disease or diabetic neuropathy). They should be used routinely for surgical
inpatients. If thigh-length stockings are not appropriate (for reasons of fit or
compliance) knee-length stockings may be used instead.
•Stocking compression profile should be equivalent to the Sigel profile (a pressure
profile for elastic stockings) and approximately:
18 mm Hg at the ankle 14 mm Hg at the mid-calf 8 mm Hg at the upper thigh
•Staff trained in the use of compression stockings should show the patient how to
wear them correctly, monitor their use and provide assistance when needed.
•Patients should be encouraged to wear stockings from admission until they return
to their normal level of mobility.
•Intermittent pneumatic compression or foot impulse devices may be used
instead of, or as well as, graduated compression stockings while patients are in
hospital.

31. Choice of prophylaxis:
Pharmacological
Choice depends on co-morbidities (e.g renal failure), a patient's wishes and
local policies. Options include:
Anticoagulants, Both oral and parenteral.
Oral- Warfarin
Parenteral: UFH LMWH Pentasaccharide(Fondaparinux)
Two new agents, dabigatran and rivaroxaban, have recently been licensed
for use in orthopaedic thromboprophylaxis.
-Patients with high risk and those having orthopaedic surgery should be
offered LMWH. Fondaparinux is an effective and safe alternative.
-Consideration should be given to the risks and benefits of stopping pre-
existing anticoagulation or antiplatelet therapy before surgery.
-Pharmacological prophylaxis may need to be stopped if regional anaesthesia
is employed to minimise the risk of haematoma (the timing depending on the
type of anticoagulant and the type of procedure)

32. Oral Anticoagulant- Warfarin
Dose- starts from 5 mg PO daily.
 Acts by inhibiting Vit. K reductase enzyme, thereby
depleting Vit. K-dependent clotting factors II, VII,
IX and X.
 Good oral absorption but requires 4-5 days to
achieve full anticoagulant effect
 Combine with parenteral till INR reaches atleast 2.0
 Monitor INR twice weekly for first 2 weeks, then
weekly for 2 weeks, then less frequently.

33. Recommended INR?
Recommended INR for various indications
are as follows-
Prophylaxis of DVT 2 - 2.5
Treatment of DVT  2 - 3
Recurrent VTE, MI, prosthetic heart valve
disease  3 - 3.5

34. Parenteral- UFH
Derived from porcine intestinal mucosa
 Promotes Anti-Thrombin mechanism and
inactivates Thrombin and Factor Xa
 DVT Prophylaxis dose
5,000 U SC Q8-12H aPTT monitoring not needed
Therapeutic Dosing
i/v Bolus (80U/Kg) + i/v continuous infusion (18U/Kg/hr)
 Safe in patients with Renal Dysfunction

35. Parenteral- LMWH
ENOXAPARIN, TINZAPARIN, DALTEPARIN
Produced by chemical or enzymatic cleavage of UFH
 Inactivates factor Xa to a greater extent than Thrombin.
 Minimally prolongs the aPTT
 Factor Xa monitoring is required in Renal dysfunction,
Obesity and Pregnancy
 DVT Prophylaxis dose
Enoxaparin 40 mg SC once daily for 8-12days
 Drug of choice in pregnant women requiring longterm
anticoagulation for thrombosis and in those with mechanical
heart valves

36. Parenteral- LMWH
• ENOXAPARIN
1 mg/Kg SC Q12H
• TINZAPARIN
175 IU/Kg SC daily
• DALTEPARIN
200 IU/Kg SC daily
Drug of choice in cancer patients and in
those with failed oral anticoagulation.

37. • The dose and frequency is controlled by aPTT measurement
which is kept at 50-80 sec or 1.5-2.5 times the patient’s
pretreatment value. If this test is not available whole blood
clotting time should be measured and kept at 2 times the
normal value.
• After a constant maintenance infusion of 18 U/kg is
initiated, the aPTT is checked 6 hours after the bolus
and adjusted accordingly. .
• The aPTT is repeated every 6 hours until 2 successive
aPTTs are therapeutic. Thereafter, the aPTT is
monitored every 24 hours as well as the hematocrit and
platelet count.

38. Parenteral- FONDAPARINUX
• Synthetic pentasaccharide structurally similar
to Heparin
• Selective Factor Xa Inhibitor
• Monitoring of factor Xa levels similar to
LMWH (renal dysfunction)
• Dosing
FONDAPARINUX 7.5 mg SC daily

39. Selective Indirect Factor Xa
XIIa
inhibition Tissue
factor
XIa VIIa
IXa
Xa
× Antithrombin
Fondaparinux
Factor II
(prothrombin)
Fibrinogen Fibrin clot

40. Indications of warfarin
1. Prophylaxis and/or treatment of venous thrombosis and
its extension, and pulmonary embolism.
2. Prophylaxis and/or treatment of the thromboembolic
complications associated with atrial fibrillation and/or
cardiac valve replacement.
3. To reduced the risk of death, recurrent myocardial
infarction, and thromboembolic events such as stroke
or systemic embolization after myocardial infarction.

41. Heparin: Mechanism of Action
Accelerates antithrombin III activity
Antithrombin III
(Heparin)
Factor X
Factor IXa
Ca2+, PL
Factor VIIIa
Factor Xa
Prothrombin Thrombin
Factor Va
Ca2+, PL

42. Heparin Side Effects
• Bleeding
• Osteoporosis
(inhibits osteoblasts, activates osteoclasts)
– > 3 mths, > 20,000 units qd
• Thrombocytopenia
• Type I HIT
• Type II HIT (3-5%)
• Skins lesions- urticaria, papules, necrosis
• Hypoaldosteronism, hyperkalemia

43. Heparin Contraindications
• Bleeding disorders, HIT.
• Severe hypertension, threatened abortion,
piles
• SABE, large malignancies, Tuberculosis’
• Ocular and neurosurgery, LP
• Chronic alcoholics, cirrhosis, renal failure

44. BUT…What if treatment with anti-
coagulant is contraindicated???
IVC filter.

45. These pulmonary
emboli removed
at autopsy look
like casts of the
deep veins of the
leg where they
originated.

46. VTE & Pregnancy
Pre-pregnancy counselling and a management plan should be offered to all women
who are at high risk of VTE. All pregnant women should have their risk factors
assessed and documented.
This assessment should be repeated if there is a hospital admission for any reason
or if complications develop. Thrombophilia should be excluded in women with a
previous non oestrogen-related VTE which has been provoked by a minor risk factor.
Prophylaxis should begin as soon as possible in pregnancy.
LMWH is the prophylaxis of choice, being safer and equally effective as UFH.
Any woman with three or more persistent or recurrent risk factors identified should be
considered for antenatal prophylaxis.
LMWH should not be given routinely to women who have had one previous VTE
event providing this is non oestrogen-related and they have no other risk factors but
they should be monitored closely.

47. VTE & Pregnancy
Women should be offered prophylaxis antenatally if:
They have a history of recurrent DVT
An unprovoked, oestrogen-related or pregnancy-related VTE
A previous VTE and a first-degree relative with a history of DVT or proven
diagnosis of thrombophilia
Women with asymptomatic inherited or acquired thrombophilia should be
monitored closely antenatally but should be referred to a local expert if:
They have antithrombin deficiency
The have more than one thrombophilic defect (including homozygosity for
factor V Leiden)
They have additional risk factors
Women given LMWH should not have any more LMWH injections if they
have vaginal bleeding or go into labour.

48. After delivery
Mobilisation should be encouraged during and after labour
Fluid intake should be encouraged
Women with two or more risk-persisting risk factors should be considered
for LMWH for 7 days postnatally.
Women with three or more such factors should be given graduated
compression stockings as well as LMWH
Women with BMI>40kg/m2 should be considered for LMWH prophylaxis
for 7 days postnatally
The decision to initiate LMWH at the time of discharge for women who have
had emergency or elective LSCS and duration of treatment will depend on
what risk factors are present (age, weight, co-morbidities, family history of
thrombophilia)

49. After delivery
Women who have had a VTE before the current pregnancy should be
considered for LMWH for six weeks postnatally.
If they are receiving LMWH before pregnancy, preventive doses of LMWH
should be given until 6 weeks postpartum. A postnatal risk assessment
should then be made.
Patients on long-term warfarin can recommence this when the risk of
haemorrhage is low
Breast-feeding is no contra-indication to either warfarin or LMWH
Repeated risk assessments for VTE should be carried out if women
develop intercurrent problems, or they require surgery or readmission for
any reason in the puerperium
For women with additional risk factors lasting >7 days postpartum –
eg: wound infection, prolonged admission - thromboprophylaxis should be
continued for up to six weeks or until the risk factors have resolved