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.

  • calf pain, lower extremity swelling (>3cm c/w unaffected side-10cm below tibial tuberosity, circumference)
  • erythema, warmth, tenderness +homan’s sign (calf pain on dorsiflexion)

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

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.


  • 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

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

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

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

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.

  • up to 40% of DVT patients have thrombophilias, especially unprovoked 
  • major ones are APC resistance, protein C or Protein S deficiency, APS, prothrombin gene mutation, Factor V leiden.
  • suggested to Ix in young pt, + fmHx or recurrent DVT/PE pt
Posted in 21 DVT, 99 Priority Topics, FM 99 priority topics, Resp

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