Recently bedridden ≥3 days or major surgery in the past 12 weeks
Paralysis, paresis or recent plaster immobilization of affected leg
Previously documented DVT
Calf swelling >3cm more than contralateral leg
Swelling of whole leg
Localised tenderness along deep venous system
Dilated collaterals present (NOT varicose veins)
Pitting oedema confined to symptomatic leg
An alternative diagnosis is at least as likely
Initial management of deep vein thrombosis
After history and examination, calculate the Wells score:
If <2, perform a D-dimer test – if negative, DVT is excluded. Consider alternative diagnoses.
If Wells score ≥2, or if the D-dimer is positive, proceed to Doppler and compression ultrasound examination of the venous system. If scanning is delayed, start precautionary anticoagulation whilst it is awaited.
Proximal DVT requires treatment
There are no trial data to inform whether below-knee DVT requires treatment, and some centres will not scan below the knee for that reason.
If diagnosis confirmed, bloods prior to treatment:
PT and APTT
Treatment with anticoagulation
Initial treatment with one of the following:
Low molecular weight heparin (enoxaparin, dalteparin, or tinzaparin at a therapeutic dose, depending on weight, given sub-cutaneously)
Apixaban (an oral Xa inhibitor, given at a dose of 10mg twice daily for 7 days, then 5mg twice daily thereafter. It is contraindicated if eGFR<15ml/min.)
Rivaroxaban (an oral Xa inhibitor, given at a dose of 15mg twice daily for 21 days with food, then 20mg once daily thereafter. It is contraindicated if eGFR<15ml/min)
Further management of deep vein thrombosis
After initial treatment, anticoagulation can continue with one of the above anticoagulants, or switch to warfarin or dabigatran.
Warfarin initiation requires frequent INR monitoring, and concurrent LMWH at a therapeutic dose until INR>2 for 24 hours. This is because warfarin also inhibits synthesis of proteins C and S, which have a shorter half life than other vitamin K-dependent clotting factors, and so the initial effect of warfarin is prothrombotic.
Dabigatran (an oral thrombin inhibitor) is given at a dose of 150mg twice daily, or 110mg twice daily if elderly, if eGFR<50ml/min or receiving concurrent verapamil. It is contraindicated if eGFR<30ml/min.
Duration of anticoagulation depends on previous history and whether the DVT was provoked by a transient risk factor e.g. surgery.
Patients with recurrent unprovoked VTE should receive long-term anticoagulation.
A first episode of provoked VTE requires anticoagulation for at least 3 months, and consider re-scanning for residual thrombus, in which case extend anticoagulation to 6 months.
Use clinical judgement to assess risk of recurrence in those with first unprovoked VTE or recurrent provoked VTE. In general, most patients do not need anticoagulation beyond 6 months but some will be at high risk of recurrence.
Stop any offending drugs e.g. combined oral contraceptive, hormone replacement therapy.
Investigation for underlying causes
Most risk factors will become apparent in the history, examination and initial testing.
Consider investigation for underlying malignancy in those over 55yrs with first unprovoked DVT
Testing for inherited thrombophilias is generally not recommended, as it does not alter management. Furthermore acute thrombus and anticoagulant drugs affect levels of clotting factors so tests are not interpretable.
In those with recurrent unprovoked DVT or thrombosis in unusual sites (e.g. arm, cerebral sinuses, splanchnic veins) consider testing for antiphospholipid syndrome (Lupus anticoagulant, anti-cardiolipin and anti-β2 glycoprotein 1), myeloproliferative neoplasms (for JAK2 mutations) and paroxysmal nocturnal haemoglobinuria (by flow cytometry).
Complications of deep vein thrombosis
The major complication is pulmonary embolism, which may be fatal. This is why treatment is needed even if there are no symptoms, urgently.
A post-thrombotic syndrome is described, including chronic pain, oedema, haemosiderin deposition and varicose veins can develop. Compression stockings are ineffective in preventing it.
Thrombus can be a nidus for infection, particularly in intravenous drug users, in whom chronic endovascular infection may initially present as occult fever.
Prognosis of deep vein thrombosis
Isolated DVT generally has a good prognosis, with rates of post-thrombotic syndrome of 5-15% depending on the definition used.
Recurrent rates depend on the severity of ongoing risk factors.