Deep Vein Thrombosis (DVT)

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.
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.
3. Identify patients likely to benefit from DVT prophylaxis.
4. Utilize investigations for DVT allowing for their limitations (e.g., Ultrasound and D-dimer).
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).
6. Consider the possibility of an underlying coagulopathy in patients with DVT, especially when unexpected.
7. Use compression stockings in appropriate patients, to prevent and treat post-phlebitic syndrome.

Diagnosis

• Pre-test probability (clinical suspicion)
  • Risk: Virchow's Triad = Stasis, endothelial injury, hypercoagulable state
    • Acquired:
      • Prior thromboembolism
      • Recent major surgery
      • Trauma
      • Immobilization
      • Antiphospholipid antibodies
      • Malignancy
      • Pregnancy
      • Oral contraceptives
      • Myeloproliferative disorders
    • Hereditary:
      • Factor V Leiden
      • Prothrombin gene mutations
      • Protein S or C deficiency
      • Antithrombin deficiency
  • Wells Score for DVT Diagnosis
    • +1 point for each of the following
      • Paralysis, paresis or recent orthopedic casting of lower extremity
      • Bedridden >3 days recently or major surgery within 4 weeks
      • Localized tenderness of the deep veins
      • Swelling of entire leg
      • Calf swelling 3 cm greater than other leg (measured 10 cm below the tibial tuberosity)
      • Pitting edema greater in the symptomatic leg
      • Non-varicose collateral superficial veins
      • Active cancer or cancer treated within 6 months
      • Previously documented DVT
    • -2 points for alternative diagnosis at least as likely as DVT (Baker's cyst, cellulitis, muscle damage, superficial vein thrombosis, post-thrombotic syndrome, inguinal lymphadenopathy, extrinsic venous compression)
    • Score <2 = 6% DVT, ≥2 = 28% DVT
  • Upper Extremity DVT
    • Risk: Central venous catheter, recent pacemaker, malignancy
• Proximal Venous Compression Ultrasound (pCUS)
  • Note distal thrombosis may extend proximally in 20% (repeat in 7 days if suspect DVT)
  • Recurrent DVT can be difficult to diagnose due to residual compression abnormalities from previous DVT - must compare CUS results to previous study for new findings
• D-Dimer

Treatment

• Patients with moderate-high suspicion of DVT (unless high risk of bleed) should start anticoagulation before diagnosis
• Anticoagulate for initial 3 months, consider indefinite in unprovoked and cancer (and low risk bleeding):
  • LMWH or IV heparin (5000 units bolus then 20 units/kg/hr target aPTT 2-3x control aPTT) overlap with warfarin for minimum 5 days and INR >2 for minimum 2 days
    • Consider Warfarin in valvular A Fib, CrCl<30, Antiphospholipid syndrome, Weight >120kg, Gastric bypass, Liver failure
  • DOAC
    • Apixaban 10mg PO BID x 1 week, then 5mg PO BID (can decrease to 2.5mg PO BID after 6 months)
    • Rivaroxaban 15mg PO BID x 3 weeks then 20mg PO daily (can decrease to 10mg PO daily after 6 months)
    • Note: Dabigatran and Edoxaban require 5-10 day initial treatment bridge with LMWH
  • Subcutaneous LMWH (eg. Dalteparin 100 U/kg SC daily or Enoxaparin 1.5mg/kg SC daily) or IV heparin x 5-10 days, then dabigatran 150mg PO BID
  • LMWH x 1 month then DOAC or warfarin
• LMWH preferred in Cancer and in Pregnancy, advantages include fixed/simple-dosing and lower HIT
  • There is some evidence that apixaban can be used as an alternative for patient with cancer who do not want injections (but avoid in upper GI malignancy due to increased rate of bleeding)
• Only consider Aspirin in those who are adverse to long-term anticoagulation (32% reduction of recurrent VTE vs 82% when on oral anticoagulants)
• Isolated distal DVT anticoagulation only if symptomatic and risk factors for extension (severe symptoms, >5cm in length, multiple deep veins, close to popliteal veins, no reversible risk factor, previous VTE, in-patient, positive D-dimer) or progression on imaging
• Superficial vein thrombosis can be treated with topical/oral NSAIDs for symptoms, if >5cm consider low-intermediate dose LMWH

Prophylaxis

• Hip/knee arthroplasty, hip fracture = 14-35 days
• Major orthopedic trauma, Complicated Spine Surgery, Isolated below-knee fracture, L/E amputation, bedrest = until discharge

Post-thrombotic syndrome (PTS)

• Signs of chronic venous insufficiency (usually 6 months) after a DVT (extremity pain, heaviness, cramps, paresthesias, pruritus, venous dilation, edema, pigmentation, skin changes, and venous ulcers)
• Occurs in 50% of patients within one year of thrombosis, 5-10% severe PTS
• Risk:
  • Elderly, obesity
  • Smoking
  • Primary venous insufficiency, varicose veins
  • Proximal DVT, residual thrombus after treatment, recurrent DVT, inadequate anticoagulation
• Treatment (similar to chronic venous disease)
  • Smoking cessation, weight loss if obesity
  • Elevation
  • Exercise training
  • Compression stockings/bandages (30-40mmHg) or Compression device
• Prevention
  • If at risk of PTS, consider compression stockings (start within two weeks of diagnosis, after anticoagulation started, and continue for two years)