Deep Vein Thrombosis
Also known as DVT, Blood clot in the leg
This article is general health information for the selected condition. It is not a diagnosis and does not replace clinical judgement. If you have questions or need treatment advice, please consult a qualified healthcare professional.
What is deep vein thrombosis?
Deep vein thrombosis is a blood clot in a deep vein, most often in the calf or thigh. The immediate danger is that part of the clot can break away and travel to the lungs as a pulmonary embolism, which can be fatal. Sudden breathlessness or chest pain in someone with a swollen leg is a medical emergency.
Causes
- Reduced blood flow from immobility
- Injury to the vein wall
- Increased blood clotting tendency
- Surgery, particularly hip and knee replacement
- Cancer and its treatments
Symptoms
- Swelling of one leg
- Pain or cramping, often in the calf
- Warmth over the affected area
- Red or discoloured skin
- Veins that appear more prominent
- Sudden breathlessness or chest pain if clot travels to the lungs
Risk factors
- Recent surgery or hospital admission
- Prolonged immobility including long haul travel
- Pregnancy and the postnatal period
- Combined hormonal contraception or hormone therapy
- Cancer
- Obesity and smoking
- Inherited clotting disorders
Diagnosis
- Clinical probability scoring such as the Wells score
- D dimer blood test to help exclude clot in low risk patients
- Compression ultrasound of the leg veins
- CT pulmonary angiogram if embolism is suspected
- Thrombophilia testing in selected cases
Treatment
- Anticoagulation, usually with a direct oral anticoagulant
- Low molecular weight heparin in pregnancy and cancer
- Treatment for at least three months, longer if risk persists
- Compression stockings for persistent swelling
- Early mobilisation
- Catheter directed thrombolysis in selected extensive clots
Self care
- Take anticoagulation exactly as prescribed and never skip doses
- Keep moving and walk regularly rather than resting the leg
- Wear compression stockings if these have been recommended
- Elevate the leg when sitting to reduce swelling
- Carry an anticoagulant alert card
- Move about and stay hydrated on long journeys
When to see a doctor
Book an appointment if:
- Swelling or pain that is not improving on treatment
- Unusual bruising, nosebleeds or heavy periods while anticoagulated
- Before any planned surgery or dental procedure
- Planning pregnancy, since some anticoagulants must be changed
- Persistent leg swelling and skin changes months afterwards
Some symptoms need emergency care rather than an appointment. See the warning signs listed above.
Prevention
- Move regularly on long flights and journeys and stay hydrated
- Follow prevention measures after surgery, including early mobilisation
- Keep to a healthy weight and stay active
- Stop smoking
- Discuss clot risk before starting combined hormonal contraception
- Wear prescribed compression stockings when advised
Outlook
With prompt anticoagulation most clots resolve or become stable and the risk of pulmonary embolism falls sharply. Treatment usually lasts at least three months, and longer where the cause persists. Around a third of people develop post thrombotic syndrome with ongoing swelling, aching or skin changes, which compression and early mobilisation help reduce.
Common questions
What makes deep vein thrombosis an emergency?
A fragment of clot can travel to the lungs and block blood flow. Sudden breathlessness, sharp chest pain worse on breathing in, coughing blood or collapse require emergency care immediately.
How can clots be prevented on long flights?
Move and walk regularly, flex the calves while seated, stay hydrated and avoid excess alcohol. People at higher risk may be advised to wear compression stockings or, occasionally, to take preventive anticoagulation.
Can a clot in the leg be treated at home?
Many uncomplicated cases are treated as an outpatient with oral anticoagulants. Extensive clots, significant symptoms or suspected pulmonary embolism generally require hospital assessment first.
References
Important: Dard AI is not a medical device and does not diagnose, treat, or replace clinician judgement. This article is general information only. Always consult a qualified healthcare professional about diagnosis and treatment, and seek emergency care for severe or rapidly worsening symptoms.