Deep venous thrombosis (DVT)
Questionnaire/history:
Unilateral limp pain (often below the knee)?
Limb swelling/oedema?
Local tenderness over the venous system?
Skin changes?
- Erythema?
- Warmth?
Venous distension?
Limb circumference > 3 cm versus unaffected leg?
(Note: classic triad of pain, swelling and erythema in < 30%)
Past medical history?
Family history?
Current medication?
Known drug allergies?
Examination:
(Note: DVT cannot be diagnosed or excluded on the basis of clinical symptoms alone)
Limb swelling/oedema?
Local tenderness over the venous system?
Skin changes?
- Erythema?
- Warmth?
Venous distension?
Limb circumference > 3 cm versus unaffected leg?
(Note: classic triad of pain, swelling and erythema in < 30%)
Risk assessment:
Active cancer (treatment or palliation within 6 months)?
Bedridden recently (> 3 days or major surgery within 12 weeks)?
Calf swelling > 3 cm compared to the other leg (measured 10 cm below tibial tuberosity)?
Collateral (nonvaricose) superficial veins present?
Entire leg swollen?
Localized tenderness along the deep venous system?
Pitting edema, confined to symptomatic leg?
Paralysis, paresis, or recent plaster immobilization of the lower extremity?
Previously documented DVT?
Alternative diagnosis to DVT as likely or more likely (-2)?
Management:
DVT likely - score ≥ 2:
Urgent referral for doppler US (ideally result within 4 hours)
- If imaging cannot be done immediately (< 4 hours) offer interim anticoagulation (see below)
- If imaging confirms DVT offer or continue anticoagulation (see below)
- If DVT is not identified on imaging check D-dimer:
--- If D-dimer is positive, stop anticoagulation (if necessary) and repeat Doppler US in 6-8 days
--- If D-dimer is negative, stop anticoagulation (if necessary) and consider alternative cause
DVT unlikely - score < 2:
Arrange D-dimer test with result available within 4 hours
Consider a point of care test if laboratory test not immediately available
If using point of care D-dimer use quantitative test
Consider age-adjusted D-dimer thresholds for > 50yrs - reduces false positives and unnecessary imaging
If D-dimer test result cannot be obtained within 4 hours offer interim anticoagulation (see below)
- If D-dimer is positive refer urgently for Doppler US and follow protocol above
- If D-dimer is negative then stop anticoagulation and consider alternative diagnosis
Interim anticoagulation:
Choose an anticoagulant that can be continued if DVT is confirmed (see below)
Baseline bloods (FBC, UEs, LFTs, PT, APTT) but do not wait for the results before starting anticoagulation
Anticoagulation for confirmed DVT
Offer anticoagulation for at least 3 months:
1st line:
- Apixaban 10 mg BD for 7 days then 5 mg BD or
- Rivaroxaban 15 mg BD for 21 days then 20 mg OD
If unsuitable:
LMWH for 5 days followed by dabigatran or edoxaban or
LMWH concurrently with warfarin until INR > 2.0 for 2 consecutive readings then warfarin alone
Anticoagulation in special situations:
Extremes of body weight: < 50kg (overdosed) or > 120kg (underdosed)
Monitor therapeutic levels - for most this will mean LMWH/warfarin, however
Recent guidance from ISTH July 2021 has reviewed evidence on DOACs in people with HIGH BMI and concludes 'For treatment of VTE, we suggest that standard doses of rivaroxaban or apixaban are among appropriate anticoagulant options regardless of high BMI and weight'.
Renal impairment (use estimated creatinine clearance NOT eGFR):
Estimated creatinine clearance: 15 -50ml/min:
- Apixaban - no dose adjustment required
- Rivaroxaban - after 21 days use 15 mg OD rather than 20mg
- LMWH concurrently with warfarin until INR > 2.0 for 2 consecutive readings then warfarin alone
Estimated creatinine clearance < 15ml/min:
- LMWH
- LMWH concurrently with warfarin until INR > 2.0 for 2 consecutive readings then warfarin alone
Active cancer:
Offer anticoagulation for 3-6 months
When choosing agent take into account tumour site, interactions with other drugs including cancer drugs and patients bleeding risk
Consider DOAC
If DOAC unsuitable consider LMWH alone or warfarin
For patients in remission follow standard pathway
Antiphospholipid Syndrome:
LMWH concurrently with warfarin until INR> 2.0 for 2 consecutive readings then warfarin alone
Long term anticoagulation
Provoked DVT:
Consider stopping anticoagulation after 3 months (3-6 months for active cancer) if provoking factor is no longer present and clinical course has been uncomplicated
Unprovoked DVT:
Consider continuing anticoagulation beyond 3 months (6 months for active cancer) based on balance of risks of VTE versus bleeding risk. Take patient preference into account
Patients with low bleeding risk are likely to continue to benefit from continuing anticoagulation
HAS-BLED score can be used to assess risk. Consider stopping anticoagulation if score >4 and not modifiable
For patients who decline continued anticoagulation consider Aspirin 75-150 mg OD
Investigation for cancer
Do not offer further investigations for cancer to patients with unprovoked DVT or PE unless they have relevant clinical symptoms or signs
Review medical history, offer examination and baseline bloods
Thrombophilia screening
Consider antiphospholipid antibodies in unprovoked DVT if it is planned to stop anticoagulation
Consider hereditary thrombophilia screen in unprovoked DVT when a first-degree relative has a history of DVT or PE and it is planned to stop anticoagulation
Do not offer testing to those continuing on anticoagulation
Do not offer testing to patients with a provoked DVT
Resource(s):
CKS 2018