Deep Vein Thrombosis

Definition: DVT is the formation of a blood clot in a deep vein which partially or completely obstructs blood flow. Thrombus can dislodge and travel in the blood, commonly to the pulmonary arteries, known as a pulmonary embolism (PE). Provoked DVT - transient risk factors, Unprovoked DVT occurring the absence of transient risk factors.

Risk factors: Continuing/Intrinsic

Male sex

Heart failure

Being overweight or obese

Medical illness eg acute infection

Age over 60 years

Acquired or familial thrombophilia

Cancer (known or undiagnosed)

Inflammatory disorders

History of DVT

Varicose veins

Risk factors: Temporary

Chemotherapy

Significant immobility

Recent trauma

Prolonged travel

Recent hospitalisation

Significant trauma or direct trauma to a vein

Recent major surgery

Hormone treatment

Pregnancy and postpartum

Dehydration

When to suspect

Tenderness

Skin changes, which include oedema, redness and warmth

Calf swelling (more rarely, swelling of the entire leg)

Vein distention

Unilateral localised pain (usually throbbing) occurs when walking/weight bearing

Carry out physical examination and review medical history to exclude an alternative cause

Assess leg/thigh swelling. Measure circumference of the leg 10cm below tibial tuberosity and compare with asymptomatic leg - difference of more than 3cm increases the probability of DVT diagnosis

Assess for oedema and dilated collateral superficial veins on the affected side

Calculate two-level DVT Wells Score

Differential Diagnosi

Cardiovascular disorders: superficial thrombophlebitis, post-thrombotic syndrome, venous obstruction or insufficiency or external compression of major veins, acute arterial ischaemia, vasculitis, heart failure.

Other conditions: Ruptured Baker's cyst, cellulitis, dependent oedema, lymphatic obstruction, septic arthritis, cirrhosis, nephrotic syndrome and compartment syndrome.

Physical trauma - calf muscle tear/Achilles' tendon tear, calf muscle haematoma, fracture.

Management

If starting interim anticoagulation therapy: obtain baseline blood tests including full blood count, renal and hepatic function, prothrombin time (PT) and activated partial thromboplastin time (APTT) - do not wait for results, review/act on results of baseline drugs within 24 hours of starting interim therapeutic anticoagulation therapy.

Follow up - if no contraindications those with DVT will require maintenance treatment of oral anticoagulation following acute treatment. - Specialists will make clinical decisions of choice of anticoagulant/duration of treatment. Treatment usually for at least 3 months.

Interim therapeutic anticoagulation: offer apixaban or rivaroxaban first line (considering contraindications dependent on the individual comorbidities, contraindications and the persons preference). Consider a therapy which can be continued if required.

DVT Wells Score

  • scores 1 point for each

Recently bedridden for 3 days or more, or major surgery within the last 12 week requiring general or regional anaesthesia

Localized tenderness along the distribution of the deep venous system (such as the back of the calf)

Paralysis, paresis, or recent plaster immobilization of the legs.

Entire leg is swollen

Active cancer (treatment ongoing within the last 6 months or palliative)

Calf swelling by more than 3cm compared with asymptomatic leg

Pitting oedema confined to symptomatic leg

Collateral superficial veins (non-varicose)

Previously documented DVT

Subtract two points if an alternative cause is considered at least as likely.

DVT is likely if the score is two points of more and unlikely if the score is one point or less.

If unprovoked DVT ensure person is investigated for possibility of undiagnosed cancer and offer thrombophilia testing (if appropriate)

Unlikely DVT - D-dimer test with results within 4 hours if results not able to be obtained in 4 hours offer interim therapeutic anticoagulation. If positive - arrange proximal leg vein ultrasound. If negative - stop therapeutic anticoagulation and consider alternative diagnosis.

Advise on: how to take anticoagulatants, duration of treatment and monitoring requirements, possible adverse effects and interactions, how it may affect dental treatment, risks associated with extended travel, when and how to seek medical help. Do not offer elastic graduated compression stockings to prevent post-thrombotic syndrome or VTE recurrence.

Likely DVT dependent on score - Refer to HOT clinic - leg ultrasound, d-dimer test, interim therapeutic anticoagulation with ultrasound results within 24 hours.

Refer immediately for same-day assessment and management if DVT is suspected in a women who is pregnant or has given birth within the last 6 months. For all others with suspected use DVT Well's Score