Venous thromboembolism
From IDWiki
Epidemiology
- 1/1000 individuals per year
- 2/3 DVT, 1/3 PE
- 50% of PEs unprovoked
Risk Factors
- Demographic
- Age
- Sex
- Race
- BMI
- Provoking factors
- Surgery/trauma
- Acute medical illness
- Immobility
- Hormonal therapy and pregnancy
- Cancer and chemotherapy
- Hereditary thrombophilias
- Biochemical/Acquired conditions
- Antiphospholipid antibody syndrome
- Elevated Factor VIII
Clinical Manifestations
History
- Assess if it was provoked by a transient risk factor:
- Surgery, hospitalization, or plaster cast immobilization within the last 3 months
- Central venous catheter-associated VTE
- Estrogen therapy, pregnancy, flight over 8 hours, recent leg injury or immobilization within the past 6 weeks
Signs & Symptoms
- 3+ cm difference in calf circumference measured 10 cm below the tibial tuberosity
- Dilated non-varicose veins
- Tenderness over deep veins
- Homan's sign: flexing the ankle causes calf pain (poor sensitivity and specificity)
- Phlegmasia cerulea dolens
Well's Criteria for DVT (C3PO + R2D2)
- Cancer within 6 months
- Calf diameter increase >3 cm
- Collateral superficial veins (non-varicose)
- Pitting edema confined to symptomatic leg
- Oedema of the entire leg
- tenderness along deep venous system (t = + in mnemonic)
- Recently bedridden for > 3 days
- Recent immobilization of leg (cast, paralysis)
- DVT in the past
- Diagnosis other than DVT likely (2 points off)
Well's Criteria for PE
- Tachycardia (> 100 bpm) 1.5 points
- Hemoptysis 1 point
- Immobilization (< 4wks) 1.5 points
- Signs or symptoms of DVT 3 points
- Active malignancy (<6/12) 1 point
- Previous DVT or PE 1.5 points
- Etiology most likely PE 3 point
Investigations
- Generally don't screen for hereditary thrombophilias, as it does not change management
- No need to screen for occult malignancies (based on SOME trial 2013
- CBC, renal and liver function testing, chest X-ray
- Age-appropriate cancer screening
Management
- Anticoagulation
- Acutely, can use unfractionated heparin infusions, if the patient may require interruption of therapy
- Avoid long-term UFH, which is the only anticoagulant shown to have a higher risk of recurrence
- Outpatient treatment options:
- Warfarin 10/5/5 then INRs
- DOACs
- Apixaban 10mg BID x7d then 5mg BID x3wk then 2.5 BID
- Rivaroxaban 15mg BID x21days then 20mg OD
- Dabigatran requires LMWH induction, for some reason
- Low-molecular weight heparins preferred in malignancy (CLOT trial)
- Duration of treatment is 3 months if provoked or indefinitely if unprovoked
- For long-term prophylaxis, can consider ASA or rivaroxaban 10mg (EPCAT II trial)
- Thrombolysis of unclear benefit, but probably should be used if patient is unstable from PE
- IVC filter
- If there is a contraindication to anticoagulation
- Probably only necessary if acute clot
- Retrievable up to a year
Prognosis
- High risk of recurrence for unprovoked VTE
- After first unprovoked episode, cumulative incidence for recurrence is 16% at 2 years, 25% at 5 years, and 36% at 10 years.
- Men have a 1.4x higher risk
- Positive D-dimer has 2x higher risk
- Proximal DVT 5x higher than distal DVT
- Proximal DVT 1.4x higher than PE alone, and DVT + PE is 1.5x higher than PE alone
- 4% case fatality with recurrent episode
- Provoked is about a third the risk of unprovoked
- The stronger the provoking factor (i.e. major surgery), the lower the recurrence risk
