Health condition · Clinically reviewed
Deep vein thrombosis, a preventable — and treatable — clot.
A clot forming in a deep vein, usually in the leg. Left untreated it can cause pulmonary embolism. Modern anticoagulation makes home-based treatment the norm.
Why trust this guide
- 01
Clinically reviewed
Written by our editorial team and reviewed by a registered UK clinician before publication.
- 02
Sourced, not summarised
Every claim is checked against NICE, the British Society for Haematology or a peer-reviewed source you can see at the end.
- 03
Updated for 2026
Reflects current UK guidance on diagnosis, DOAC treatment and prevention of post-thrombotic syndrome.
Key facts
Deep vein thrombosis at a glance.
The essentials, in plain English — what it is, how it is diagnosed, how it is treated in the UK today, and what to watch for afterwards.
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What it is
A thrombus (blood clot) forming in a deep vein, most often in the calf, thigh or pelvis.
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Provoked vs unprovoked
Provoked DVT follows a clear trigger (surgery, immobility, hormones, pregnancy); unprovoked DVT has no obvious cause and needs a wider work-up.
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Risk assessment
The Wells score is used to stratify probability before any imaging or blood test.
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How it is diagnosed
D-dimer blood test combined with a compression duplex Doppler ultrasound of the leg.
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First-line treatment
A direct oral anticoagulant (DOAC) - rivaroxaban or apixaban - is standard, usually taken at home.
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Long-term consequence
Post-thrombotic syndrome - chronic swelling, aching and skin changes - affects up to a third of patients.
Why this guide matters
A clot in the leg, but the risk is in the lungs.
DVT is treatable — often at home — but only if it is spotted early. The three points below shape everything else on this page.
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Early diagnosis prevents PE
The most serious complication — pulmonary embolism — is almost entirely preventable with prompt anticoagulation.
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DOACs changed the game
A tablet at home has replaced the injections and INR clinics that used to dominate treatment.
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Cause matters as much as clot
Whether the DVT was provoked or unprovoked shapes how long you take anticoagulation and what tests come next.
How the diagnosis is made
From first suspicion to a confirmed plan.
The steps a UK clinician will normally follow, in order — so you know what to expect and why.
Phase 1 · Assessing
Wells score and D-dimer
Phase 2 · Confirming
Imaging and specialist tests
Phase 3 · Managing
Work-up and referral
- 01
Assessing
Wells score assessment
A quick clinical risk score that estimates the probability of a DVT before any test.
- 02
Assessing
D-dimer blood test
A sensitive marker of clot breakdown - a normal result in a low-risk patient effectively rules DVT out.
- 03
Confirming
Compression duplex ultrasound of the leg
The definitive first-line scan - a Doppler that visualises the deep veins and any clot within them.
- 04
Confirming
CTPA if PE suspected
A CT pulmonary angiogram if chest pain, breathlessness or oxygen changes suggest the clot has travelled to the lungs.
- 05
Confirming
Consider thrombophilia screen
Offered in unprovoked DVT or a strong family history - a set of blood tests looking for inherited clotting tendencies.
- 06
Managing
Malignancy work-up if unprovoked
A focused review, examination and age-appropriate cancer screening - unprovoked DVT can be the first sign.
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Managing
Haematology consultation for complex cases
Recurrent, unusual-site, pregnancy-related or bleeding-risk cases are managed jointly with a specialist.
Typical timeline: same-day to 48 hours from suspicion to a confirmed diagnosis and starting treatment.
Symptoms
What deep vein thrombosis actually feels like.
Classically one-sided leg pain, swelling and warmth — but the danger sign is anything from the chest.
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Unilateral leg pain
A dull ache or cramp - usually in one calf or thigh - that does not settle with rest.
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Leg swelling
One leg noticeably bigger than the other, often with a tight, stretched feeling.
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Redness
Discoloration - red, purple or bluish - along the affected vein or over the calf.
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Warmth
The affected leg feels warmer to touch than the other one.
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Tenderness along vein
A cord-like tender area on pressing over the deep vein, particularly the calf.
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Recent immobility, surgery or hormones
Long flights, hospital stays, plaster casts, the combined pill, HRT or pregnancy all raise the risk.
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Chest pain or breathlessness
A red flag for pulmonary embolism - the clot has broken off and travelled to the lungs.
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When to seek urgent care
Sudden breathlessness or chest pain - call 999. This may be a pulmonary embolism.
Treatment
How DVT is treated in the UK.
Anticoagulation first, with tailored options for the more complex cases — what each treatment does, and where it fits.
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DOAC first-line
Rivaroxaban or apixaban - taken as a tablet, no routine blood monitoring needed, treatment usually starts the same day.
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LMWH bridge if unstable
Low-molecular-weight heparin injections when a DOAC is not suitable straight away, or in cancer-associated thrombosis.
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Warfarin (specific cases)
Still used in mechanical heart valves, antiphospholipid syndrome and severe renal impairment - INR monitoring required.
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Compression stockings
Graduated compression to relieve symptoms and reduce the risk of post-thrombotic syndrome.
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Thrombolysis
Clot-dissolving therapy reserved for large or limb-threatening iliofemoral DVT in selected patients.
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IVC filter
A device placed in the inferior vena cava when anticoagulation is contraindicated - short-term protection against PE.
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Thrombophilia review
Haematology-led assessment for inherited clotting disorders in unprovoked, recurrent or family-history cases.
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Long-term anticoagulation planning
A shared decision at 3-6 months on whether to stop, extend or continue treatment indefinitely.
What this guide is based on
The sources behind every claim on this page.
UK national guidance and specialist society standards, current at the time of last review.
Key references
Guidelines and standards we relied on.
A quiet reminder
This guide is for information, not medical advice.
Your clinician knows your history and can tell you which parts apply to you. If in doubt about a leg or chest symptom, seek urgent assessment.
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National Institute for Health and Care Excellence (NICE). Venous thromboembolic diseases: diagnosis, management and thrombophilia testing (NG158).
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British Society for Haematology. Guidelines on the diagnosis and management of venous thromboembolism.
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Thrombosis UK. Patient information on DVT, PE and anticoagulation.
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European Society of Cardiology. Guidelines for the diagnosis and management of acute pulmonary embolism.
Red flags
When DVT becomes an emergency.
Most DVTs are managed at home. These are the situations that need urgent, in-person assessment — often today.
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Sudden breathlessness
A hallmark of pulmonary embolism - call 999. Do not drive yourself.
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Chest pain
Especially sharp, pleuritic pain that worsens with breathing - urgent assessment.
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Haemoptysis
Coughing up blood in the context of leg symptoms - PE until proven otherwise.
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Syncope
A blackout or collapse with a DVT risk profile suggests a large clot compromising circulation.
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Massive limb swelling
A tense, dusky or cold leg - possible extensive iliofemoral clot needing same-day imaging.
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Skin ulceration
A non-healing ulcer with chronic leg swelling suggests advanced post-thrombotic damage.
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Post-op DVT with instability
Any post-surgical patient with new leg or chest symptoms needs urgent assessment.
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Pregnancy with DVT symptoms
Any raised suspicion in pregnancy needs same-day imaging - D-dimer alone is unreliable.
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Bilateral DVT
Clots in both legs suggest a proximal (pelvic or IVC) obstruction or a strong pro-thrombotic driver - urgent work-up.
Living with it
A finite treatment, but a lasting awareness.
Four things that make the biggest difference day to day — habits, monitoring, medication safety and follow-up reviews.
A quiet reminder
Consistency beats intensity, every time.
Steady habits — daily anticoagulant, regular walking, compression when advised — do more than any short burst of effort.
- 01 Daily habits
Move often, hydrate well
Regular walking, calf exercises and good hydration all reduce the chance of a further clot.
- 02 Monitoring
Watch the affected leg
Chronic swelling, aching or skin changes should be reviewed - early compression treatment helps.
- 03 Medication
Anticoagulant safety
Never miss doses or double up. Report unusual bruising, bleeding or a planned procedure to your clinician.
- 04 Reviews
A decision at 3-6 months
Your team will review whether to stop or continue anticoagulation based on cause, risk of recurrence and bleeding risk.
Frequently asked
Everything we get asked about deep vein thrombosis.
Quick answers on diagnosis, DOAC treatment, duration of therapy and when to worry.
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What is deep vein thrombosis?
A blood clot forming in a deep vein - most commonly in the calf, thigh or pelvis. Left untreated the clot can break off and travel to the lungs, causing a pulmonary embolism.
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How is DVT diagnosed?
A Wells score estimates probability. A D-dimer blood test helps rule it out in lower-risk patients. Compression duplex Doppler ultrasound of the leg confirms the diagnosis.
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What is the first-line treatment for DVT in the UK?
A direct oral anticoagulant (DOAC) - rivaroxaban or apixaban - taken at home for at least three months (NICE NG158).
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How long will I need to take anticoagulation?
A minimum of three months for a provoked DVT. Unprovoked or recurrent DVT often needs longer or indefinite treatment - a shared decision based on recurrence and bleeding risk.
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What is post-thrombotic syndrome?
Chronic swelling, aching, heaviness and skin changes in the affected leg after a DVT. It affects up to a third of patients and is reduced by early compression therapy.
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When should I call 999?
Sudden breathlessness, chest pain, coughing up blood or a collapse - any of these with a suspected or confirmed DVT could mean a pulmonary embolism. Call 999.
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