DVT – Thrombosis Canada 2014

1) In patients complaining of leg pain and/or swelling, evaluate the likelihood of deep venous thrombosis (DVT) as investigation and treatment should differ according to the risk.

4 Utilize investigations for DVT allowing for their limitations (e.g., Ultrasound and D-dimer).

Dx strategy:

1. Hx and PE focused on the components of the Wells score
   • Low Wells % –> d-dimer
   • Moderate Wells % –> d-dimer can be used, but most clinicians prefer US
   • High Wells % –> proximal or whole leg US
2. Pt with a negative proximal US – f/u proximal US after 5-7 days to r/o extension of a distal DVT
3. Distal: confined to deep calf veins vs Proximal: popliteal, femoral, iliac veins
4. Pathogenesis: Virchow triad – Endothelial damage, Stasis, hypercoagulability

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2 In patients with high probability for thrombotic disease (e.g., extensive leg clot, suspected pulmonary embolism) start anticoagulant therapy if tests will be delayed.

5 In patients with established DVT use oral anticoagulation appropriately, (e.g., start promptly, watch for drug interactions, monitor lab values and adjust dose when appropriate, stop warfarin when appropriate,provide patient teaching).
7 Use compression stockings in appropriate patients, to prevent and treat post-phlebitic syndrome.

Management:

• Unless US is rapidly available, pt with moderate to high suspicion of DVT should start therapy before the dx is confirmed (unless they have a high risk of bleeding)
• Out-pt management is preferred
• Initial Tx should have an immediate anticoagulant effect – warfarin monotherapy is not appropriate initially
• Compression stockings (knee-high with min 30-40mmHg at the ankle x 1yr) in pt with symptoms of post-thrombotic syndrome
  • chronic venous insufficiency 2o to DVT: pain, venous dilation, edema, pigmentation, skin changes, venous ulcers
  • At risk: High BMI, female, advanced age
• LMWH may be used as initial therapy in conjunction with warfarin for the first 5 days and until (INR) reaches at least 2.0 (for min of 48hr), or may be used as monotherapy for the full duration of treatment.
  • Dalteparin (Fragmin®): 200 U/kg SC daily or 100 U/kg SC twice daily (once daily dosing preferred).
  • Enoxaparin (Lovenox®): 1 mg/kg SC twice daily or 1.5 mg/kg SC once daily.
  • Tinzaparin (Innohep®): 175 U/kg once daily.
• Rivaroxaban (Xa inhibitor) is approved for Tx DVT without symptomatic pulmonary embolism.
  • 15 mg bid x 21 days, followed by 20 mg daily for the duration of treatment.
  • Rivaroxaban should not be used in women who are pregnant or breast-feeding.
• The Tx should continue for a min of 3mo, if recurrent, might continue Tx indefinetely

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Upper Extremity DVT – rare

• Acute and chronic arm pain, swelling discoloration, and dilated collateral veins over the arm, neck, or chest
• Risk factors
  • Central venous catheters
  • pacemaker wires
  • Malignancies
  • Thoracic outlet syndrome (Paget-schroetter syndrome)
  • Pre-test probability scores not validated

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Distal Lower Extremity DVT

• No Tx required unless progression to proximal DVT is likely
• If isolated distal DVT is found, anticoagulation may be offered if severe symptoms are present or if the risk of proximal extension is high.
• Pt may be followed with serial US for 2 weeks, after which time extension is unlikely.
• Risk factors for proximal extension:
  • Positive D-dimer
  • Extensive thrombosis
  • unprovoked
  • distal DVT
  • Cancer
  • hx of VTE
  • In-patient status

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Wells Score for DVT

Clinical Findings	Points
Paralysis, paresis or recent orthopedic casting of lower extremity	1
Recently bedridden (> 3 days) or major surgery within past 4 weeks	1
Localized tenderness in the deep veins	1
Swelling of entire leg	1
Calf swelling 3 cm greater than other leg (measured 10 cm below the tibial tuberosity)	1
Pitting edema greater in the symptomatic leg	1
Collateral non-varicose superficial veins	1
Active cancer or cancer treated within 6 months	1
Alternative diagnosis more likely than DVT (Baker’s cyst, cellulitis, muscle damage, superficial venous thrombosis, post-phlebitic syndrome, inguinal lymphadenopathy, external venous compression)	-2

Wells Score	Probability of DVT	Strata
-2 – 0	5%	Low
1 – 2	17%	Moderate
3 – 8	53%	High

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3 Identify patients likely to benefit from DVT prophylaxis.

Risk Factors:

• Age >=60
• HRT – Estrogen therapy, oral corticosteroids
• Obesity
• Pregnancy
• Active Cancer
• 1o degree relative w/ DVT or previous DVT
• hematological disorders – known thrombophilia
• Surgery, fractures, trauma
• IBD, rheumatological dz or inflammatory condition, sepsis
• nephrotic syndrome, antiphospholipid syndrome

DVT Prophylaxis for Adult Patients with Moderate or High Risk of VTE:

Anyone fulfill Virchow’s triad

• significantly reduced mobility for 3 days or more
• Medical patients with ongoing reduced mobility (compared to their usual state) AND have one or more risk factors for VTE
• Surgical procedure with a total anesthetic and surgical time 60 minutes or longer
• Acute surgical admission with an inflammatory or intra-abdominal condition
• Surgical patients with one or more risk factors for VTE
• No Contraindication to anticoagulation:
  • active bleeding,
  • risk of bleeding to critical sites (intracranial, intraspinal, pericardial, introcular, retroperitoneal),
  • untreated major bleeding disorder, acquired systemic coagulopathy

6 Consider the possibility of an underlying coagulopathy in patients with DVT, especially when unexpected.