Deep vein thrombosis (DVT) is a condition where a blood clot forms in a deep vein, most commonly in the legs. It can cause swelling, pain, and redness. The main concern with DVT is that part of the clot can break off, travel to the lungs, and cause a life-threatening condition called pulmonary embolism (PE). Early diagnosis and treatment are essential to prevent serious complications.
Causes
- Blood flow slowing down (stasis) such as during long periods of immobility
- Damage to the blood vessel wall (trauma, surgery, inflammation)
- Increased tendency of blood to clot (hypercoagulable states)
- Cancer and chemotherapy
- Pregnancy and postpartum period
- Hormone therapy, especially oestrogen-containing medications like oral contraceptives
- Genetic clotting disorders (e.g., Factor V Leiden mutation)
Pathophysiology
DVT forms when the balance between clotting and bleeding is disturbed. Three main factors contribute, known as Virchow’s triad:
- Venous stasis (slow blood flow)
- Endothelial injury (damage to blood vessel lining)
- Hypercoagulability (increased clotting tendency)
When blood stagnates, especially in the legs, clotting factors can accumulate, leading to clot formation. Inflammation and tissue damage further promote clot development, and if untreated, the clot may grow or travel
Signs and Symptoms
- Swelling in one leg (rarely both)
- Pain or tenderness, especially when standing or walking
- Red or discoloured skin over the affected area
- Warmth in the affected leg
- Distended superficial veins
In some cases, DVT can be asymptomatic and discovered only after a complication
like PE
Risk Factors
- Recent surgery (especially orthopaedic, pelvic, abdominal surgeries)
- Immobility (long flights, hospitalisation, bed rest)
- Active cancer or cancer treatment
- Pregnancy and six weeks postpartum
- Use of hormonal contraceptives or hormone replacement therapy
- Personal or family history of DVT or PE
- Obesity
- Smoking
- Older age (over 60 years)
- Inherited clotting disorders (e.g., Protein C or S deficiency)
Investigation
- Wells Score for DVT: clinical assessment tool to estimate probability of DVT
- D-dimer test: blood test detecting fibrin degradation; high levels suggest clot formation, but it is not specific
- Compression Duplex Ultrasound: first-line imaging to detect blood clots in the deep veins
- Venography: rarely used now but considered the gold standard if ultrasound is inconclusive
- Blood tests: to check kidney function before certain anticoagulants, full blood count to rule out other causes
Management
1. Non-Pharmacological Management
- Elevation of the affected limb: helps reduce swelling
- Early mobilisation: to prevent further clot formation
- Graduated compression stockings: considered after the initial treatment phase if no arterial disease is present
- Patient education: advice on recognising symptoms of PE and the importance of medication adherence
2. Pharmacological Management
- Anticoagulation therapy: mainstay of treatment
- Low Molecular Weight Heparin (LMWH) (e.g., enoxaparin) initially
- Direct Oral Anticoagulants (DOACs) like apixaban or rivaroxaban are preferred for most patients
- Warfarin is used in specific cases, with INR monitoring
- Thrombolysis: considered for massive DVT (phlegmasia cerulea dolens) but carries a bleeding risk and is reserved for severe cases
Duration of therapy:
3 months for provoked DVT (e.g., after surgery).
Longer or indefinite for unprovoked DVT or those with ongoing risk factors.
3. Surgical Management
- Inferior Vena Cava (IVC) filter placement: in cases where anticoagulation is contraindicated or if recurrent DVT occurs despite treatment
- Surgical thrombectomy: rarely performed, usually in severe cases
Complications
- Pulmonary embolism (PE): life-threatening blockage of pulmonary arteries
- Post-thrombotic syndrome: long-term complication with chronic leg swelling, pain, and skin changes
- Recurrent DVT: higher risk without proper treatment
- Chronic venous insufficiency: poor blood return from legs causing ongoing symptoms
References
- National Institute for Health and Care Excellence (NICE) Guideline NG158: Venous thromboembolic diseases: diagnosis, management and thrombophilia testing
- Royal College of Physicians (RCP) Clinical Standards for the Prevention of Venous Thromboembolism
- General Medical Council (GMC) Good Medical Practice 2024
- British Society for Haematology Guidelines on Anticoagulation for VTE