DVT Summary

Definition

  • Thrombus formation in deep veins
  • Partially/completely obstructs blood flow
  • Most common in legs/pelvis
  • Risk of pulmonary embolism

Classification

    <极>Provoked DVT (transient risk factors)
  • Unprovoked DVT (no transient risk factors)
  • Higher recurrence risk in unprovoked DVT

Clinical Features

  • Unilateral pain and swelling
  • Tenderness along deep veins
  • Skin changes (edema, redness, warmth)
  • Vein distension

Management

  • DVT Wells score assessment
  • D-dimer testing
  • Ultrasound imaging
  • Anticoagulation therapy

Deep Vein Thrombosis: Diagnosis and Management

Medical guidelines for identifying and treating deep vein thrombosis

Introduction

Deep vein thrombosis (DVT) is the term used to describe the formation of a thrombus (blood clot) in a deep vein, which partially or completely obstructs blood flow. Thrombosis usually affects the deep veins of the legs or pelvis, but may affect other sites.

Complication Risk

The thrombus can dislodge and travel in the blood, especially to the pulmonary arteries. This is known as a pulmonary embolism (PE).

Classification

DVT may be classified as provoked or unprovoked based on the presence of transient risk factors.

Provoked DVT

DVT associated with a transient risk factor such as significant immobility, surgery, trauma, and pregnancy or puerperium. The combined contraceptive pill and hormone replacement therapy are also considered to be provoking risk factors.

Unprovoked DVT

DVT occurring in the absence of a transient risk factor. The person may have no identifiable risk factor or a risk factor that is persistent and not easily correctable (such as active cancer or thrombophilia).

Risk Factors

Risk Factors

Deep vein thrombosis (DVT) is more likely to occur in people with continuing or intrinsic risk factors.

Persistent Risk Factors

  • A history of DVT
  • Cancer (known or undiagnosed)
  • Age over 60 years
  • Being overweight or obese
  • Male sex
  • Heart failure
  • Medical illness (e.g., acute infection)
  • Acquired or familial thrombophilia
  • Inflammatory disorders
  • Varicose veins
  • Smoking

Transient Risk Factors

  • Recent major surgery
  • Recent hospitalisation
  • Recent trauma
  • Chemotherapy
  • Significant immobility
  • Prolonged travel (for more than 4 hours)
  • Significant trauma or direct trauma to a vein
  • Hormone treatment
  • Pregnancy and the postpartum period
  • Dehydration

Clinical Features

Consider the possibility of deep vein thrombosis (DVT) if typical symptoms and signs are present, especially if the person has risk factors such as previous venous thromboembolism and immobility.

Typical signs and symptoms of DVT:
  • Unilateral localised pain (usually throbbing) that occurs when walking or bearing weight
  • Calf swelling (or more rarely, swelling of the entire leg)
  • Tenderness
  • Skin changes (edema, redness, and warmth)
  • Vein distension
Carry out a physical examination and review the person's general medical history to exclude an alternative cause for the symptoms and signs.
Assess leg and thigh swelling — measure the circumference of the leg 10 cm below the tibial tuberosity and compare with the asymptomatic leg. A difference of more than 3 cm between the extremities increases the probability of DVT.
Assess for oedema and dilated collateral superficial veins on the affected side.

Differential Diagnosis

Several conditions can mimic DVT and should be considered in the differential diagnosis.

Physical Trauma

  • Calf muscle tear/Achilles' tendon tear
  • Calf muscle haematoma or fracture

Cardiovascular Disorders

  • Superficial thrombophlebitis
  • Post-thrombotic syndrome
  • Venous obstruction or insufficiency
  • External compression of major veins
  • Arteriovenous fistula and congenital vascular abnormalities
  • Acute arterial ischaemia
  • Vasculitis
  • Heart failure

Other Conditions

  • Ruptured Baker's cyst
  • Cellulitis
  • Dependent (stasis) oedema
  • Lymphatic obstruction
  • Septic arthritis
  • Cirrhosis
  • Nephrotic syndrome
  • Compartment syndrome

Management

Diagnostic Approach

Use the two-level DVT Wells score to assess the likelihood of DVT and inform further management.

Clinical Images

DVT Wells Score

Score one point for each of the following:
  • Active cancer (treatment ongoing, within the last 6 months, or palliative)
  • Paralysis, paresis, or recent plaster immobilization of the legs
  • Recently bedridden for 3 days or more, or major surgery within the last 12 weeks requiring general or regional anesthesia
  • Localised tenderness along the distribution of the deep venous system
  • Entire leg is swollen
  • Calf swelling by more than 3 cm compared with the asymptomatic leg
  • Pitting oedema confined to the symptomatic leg
  • Collateral superficial veins (non-varicose)
  • Previously documented DVT
Subtract two points if an alternative cause is considered at least as likely as DVT.
The risk of DVT is likely if the score is two points or more, and unlikely if the score is one point or less.

Management Based on Wells Score

For people who are likely to have DVT:
  • Offer a proximal leg vein ultrasound scan with the results available within 4 hours if possible
  • If ultrasound cannot be carried out within 4 hours, offer D-dimer test, interim therapeutic anticoagulation, and ultrasound within 24 hours
For people who are unlikely to have DVT:
  • Offer a D-dimer test with results available within 4 hours
  • If D-dimer positive, offer ultrasound within 4 hours or interim anticoagulation and ultrasound within 24 hours
  • If D-dimer negative, stop interim anticoagulation and consider alternative diagnosis
Anticoagulation therapy:
  • Offer apixaban or rivaroxaban first line
  • Alternative options: LMWH for at least 5 days followed by dabigatran or edoxaban
  • Carry out baseline blood tests but do not wait for results before starting treatment

Follow-up of Confirmed DVT

Provided there are no contraindications, people with confirmed DVT will require maintenance treatment with an oral anticoagulant
Treatment is usually continued for at least 3 months, but duration may be longer depending on whether the DVT was unprovoked or provoked
Ensure people with unprovoked DVT are investigated for possibility of undiagnosed cancer and offered thrombophilia testing as appropriate

Complications

Serious Complications

The most serious complication of deep vein thrombosis (DVT) is death due to pulmonary embolism (PE).

Post-thrombotic syndrome — a chronic venous hypertension causing limb pain, swelling, hyperpigmentation, dermatitis, ulcers, venous gangrene, and lipodermatosclerosis.
Bleeding associated with anticoagulation treatment — most episodes are associated with a previously unknown pathological lesion (for example, duodenal ulcer).
Heparin-induced thrombocytopenia (HIT) — this may occur 5–7 days after initial exposure to heparin, but can occur in less than 1 day in people previously exposed to heparin.