Thrombolysis (clot-dissolving treatment) (Catheter-directed thrombolysis)
An urgent treatment that uses a powerful clot-dissolving drug, often delivered through a fine tube placed right at the clot, to reopen a blood vessel that has suddenly become blocked.
✓ Medically reviewed by a GMC-registered consultant · last reviewed September 2026 · next review September 2027 · how we review
In short
- Thrombolysis dissolves a blocking clot to restore blood flow, and is often an emergency treatment when a limb or organ is at risk.
- Its main and most serious risk is bleeding, including rare bleeding in the brain, so it is done in hospital with intensive monitoring.
- It is usually started urgently and the drug may run for many hours or a day or two, with repeat scans to check progress.
- It does not fix the underlying cause; you will normally need blood thinners and further tests afterwards, and sometimes surgery if the clot will not clear.
A plain-English summary. The detail — including risks and recovery — is below.
At a glance
A general guide. Your radiologist will give you advice for your situation.
Can reopen a suddenly blocked vessel and restore blood flow quickly, which may save a limb or reduce damage to an organ
People with active bleeding, a recent stroke, recent major surgery or a recent serious head injury, where bleeding risk is too high.
You stay in hospital, often on a high-dependency or intensive care unit, lying fairly still with the tube in place. Staff check you very frequently for...
Close in-hospital monitoring during and after the infusion, with clear escalation if bleeding occurs.
You stay in hospital, often on a high-dependency or intensive care unit, lying fairly still with the tube in...
Pressure is applied to the entry site and you may need to lie flat for some hours so it seals. The site is watched...
You usually remain in hospital. Blood thinners are often started or continued, and tests are done to find out why...
Timing depends on your overall condition. You will normally leave on blood-thinning medicine with a clear plan for...
What is thrombolysis (clot-dissolving treatment)?
Thrombolysis means using a medicine to dissolve a blood clot that is blocking a blood vessel. The medicine breaks down the clot so blood can flow again. It is most often used in an emergency, when a sudden clot is starving a leg, an organ or part of the body of blood and there is not much time to act.
The medicine can be given through a drip into a vein, but interventional radiologists often deliver it in a more targeted way. Using X-ray or ultrasound to see inside the body, a doctor threads a very fine tube (catheter) through a blood vessel until its tip sits in or next to the clot, then drips the clot-dissolving drug straight onto it. This can mean a smaller dose reaches the clot more directly.
The trade-off is bleeding. A drug strong enough to dissolve a clot can also stop helpful clots forming elsewhere, so there is a real risk of bleeding, including the rare but serious risk of bleeding in the brain. That is why thrombolysis is given in hospital with very close monitoring, and why doctors weigh it up carefully for each person.
Thrombolysis does not cure the reason the clot formed. You will usually still need blood-thinning medicine and tests to find out why the clot happened.
Types, options & approaches
There may be different ways to do this. The right approach depends on the clinical question and your circumstances.
Thrombolysis compared with blood thinners alone
| Thrombolysis | Blood thinners (anticoagulation) | |
|---|---|---|
| What it does | Actively dissolves the existing clot | Stops the clot growing; your body slowly reabsorbs it |
| Speed | Can reopen a vessel quickly in an emergency | Slower; clot clears over weeks |
| Main risk | Higher bleeding risk, including rare brain bleed | Bleeding risk too, but generally lower |
| Where | Hospital, with intensive monitoring | Often at home once started |
Which is right depends on how urgent and dangerous the clot is, and on your personal bleeding risk. Many clots are treated with blood thinners alone.
Preparing for your procedure
- Because thrombolysis is often an emergency, there may be little time to prepare; the team will explain things as quickly and clearly as the situation allows.
- Tell the team about any bleeding problems, recent surgery, recent stroke, head injury, stomach ulcers or pregnancy, as these affect whether the treatment is safe.
- Share a full list of your medicines, especially blood thinners or anti-platelet drugs such as warfarin, apixaban, rivaroxaban, aspirin or clopidogrel.
- Blood tests and a scan are usually done first to confirm the clot and check your blood clotting and kidney function.
- You will normally be asked not to eat or drink for a period in case sedation is needed, and a drip will be placed.
- You will usually be cared for on a high-dependency or intensive care unit so your blood pressure, the tube site and any signs of bleeding can be watched closely.
- Make sure you understand why it is being offered, the bleeding risk and what the alternatives are; ask the team to explain anything that is unclear.
What happens
For catheter-directed treatment, you lie on an X-ray table and the skin over a blood vessel (often in the groin) is numbed with local anaesthetic. Using imaging to guide the way, the interventional radiologist passes a fine tube through the vessel until its tip reaches the clot.
The clot-dissolving drug is then dripped through the tube, often slowly over several hours and sometimes for a day or two. You are usually awake but may be given something to help you relax. You may need to keep the affected limb still and lie fairly flat while the tube is in place.
Throughout, staff check your pulse, blood pressure and the tube site very frequently, and look for any sign of bleeding. Repeat scans (angiograms) are done to see whether the clot is clearing and whether the tube needs repositioning.
When the clot has dissolved enough, or the planned time is up, the drug is stopped and the tube removed. Sometimes a narrowing in the vessel that caused the clot is treated at the same time, for example with a balloon or stent.
Is this procedure right for me?
A good consultation should explore whether it's the right choice for you now — including reasons to wait or consider something else.
May not be suitable if…
- People with active bleeding, a recent stroke, recent major surgery or a recent serious head injury, where bleeding risk is too high.
- People with very high uncontrolled blood pressure or a known bleeding disorder, unless this can be corrected.
- Clots that are old, very extensive or where the limb or organ is already beyond saving.
- Situations where blood thinners alone, or surgery, are the safer or more effective option.
Delay or rearrange if…
- There is uncorrected severe bleeding or very abnormal blood clotting.
- Blood pressure is dangerously high and not yet controlled.
- Pregnancy or recent childbirth, which need careful specialist weighing of risk.
- Key information is missing, such as recent surgery, head injury or current blood-thinning drugs.
Alternatives to discuss
- Blood-thinning medicine (anticoagulation) alone, which is the usual treatment for many clots.
- Surgery to remove the clot (thrombectomy) or to bypass a blockage.
- A mechanical device to break up or remove the clot through a catheter, with little or no drug.
- Supportive care while the body reabsorbs the clot, where the clot is not immediately dangerous.
Before you decide
Use this as a shared-decision checklist. The aim is not just “can this be done?”, but whether it is right for you, now, with the risks and alternatives clearly understood.
What matters most to me?
Think about symptoms, daily life, work, caring responsibilities, sport, fertility, travel, appearance and anxiety — the right choice depends on your priorities, not just the medical facts.
What are all my options?
Ask about waiting, monitoring, medicines, rehabilitation, a smaller or larger procedure, a different test, NHS referral, or a second opinion where that would help.
What would make me pause?
Active infection, pregnancy, unstable medical problems, smoking, medicines that increase bleeding, poor support at home, or feeling pressured are all reasons to slow down and get tailored advice.
What happens if I do nothing today?
For some problems, waiting is safe; for others, delay can make treatment harder. A good consultation should explain the trade-off in plain English.
Comfort, sedation or contrast choices
If local anaesthetic, sedation, contrast or pain relief is used, ask what is planned, why, and what it means afterwards.
Benefits
- Can reopen a suddenly blocked vessel and restore blood flow quickly, which may save a limb or reduce damage to an organ
- Targeted (catheter) delivery can treat the clot directly, sometimes with a lower total dose than a whole-body drip
- May avoid or reduce the need for bigger open surgery in some situations
- For large leg-vein clots, may lower the chance of long-term leg swelling and skin problems (post-thrombotic syndrome) in selected people
- Can be combined with treating the underlying narrowing that caused the clot
Risks & complications
- Bruising, bleeding or a lump at the tube entry site
- Discomfort from lying still for a long time while the drug runs
- Needing the tube repositioned or the infusion continued longer than first hoped
- Bleeding elsewhere in the body, such as from the gut, gums or in the urine, which may mean stopping treatment
- Pieces of clot breaking off and blocking a smaller vessel further down (distal embolisation)
- Damage or narrowing of the treated blood vessel
- Allergic reaction to the X-ray contrast dye, or strain on the kidneys
- Bleeding into the brain, which can cause a stroke and can be life-threatening
- Major internal bleeding needing transfusion or further treatment
- Failure to dissolve the clot, so that surgery or another procedure is still needed
- Loss of the limb despite treatment, if blood flow cannot be restored in time
The biggest concern with thrombolysis is serious bleeding, and the most feared is bleeding in the brain. Your risk depends on your age, blood pressure, recent surgery or injury, other illnesses and which other blood-thinning drugs you take. Ask the team why they judge the benefit to outweigh the bleeding risk in your case, and what the plan is if bleeding occurs or the clot does not clear.
Published figures to discuss
Bleeding risk with thrombolysis varies a great deal with the situation, the dose and route, your age and blood pressure, recent surgery or injury, and which other blood-thinning drugs you take. Published bleeding rates differ widely between conditions (for example leg-artery clots, lung clots and stroke), so single percentages can be misleading. Your team will estimate your personal risk rather than rely on a general figure.
| Figure | Reported range | How to interpret it | Source / confidence |
|---|---|---|---|
| Serious bleeding (overall) | Reported in roughly low single-digit to higher percentages depending on the condition treated | Varies widely; the figure for one condition does not apply to another, so this should be discussed individually. | Catheter-directed thrombolysis vs anticoagulation in DVT — PMC reviewncbi.nlm.nih.govSource-linked context |
| Bleeding into the brain | Uncommon but serious; reported around the low single-figure percentage range in some settings such as stroke and lung-clot treatment | This is the most feared complication and a major reason thrombolysis is used selectively and monitored closely. | Catheter-directed thrombolysis vs anticoagulation in DVT — PMC reviewncbi.nlm.nih.govSource-linked context |
| Treatment failing to clear the clot enough | A minority, varying by clot age, size and condition treated | Some patients need thrombectomy, stenting, surgery or anticoagulation after thrombolysis. | Guide sourcesClinical context |
| Re-thrombosis after treatment | Recognised risk | Ongoing anticoagulation and treating the underlying cause are crucial once bleeding risk allows. | Catheter-directed thrombolysis vs anticoagulation in DVT — PMC reviewncbi.nlm.nih.govSource-linked context |
These are literature figures, not a personalised prediction. Your own risks and likely benefits depend on your circumstances, your health, and how your care is carried out and followed up.
What happens afterwards
Recovery depends far more on the underlying problem (such as a blocked artery, a large vein clot, a clot on the lungs or a stroke) than on the treatment itself. You will stay in hospital while you are monitored and while the cause is investigated.
- Tenderness, bruising or a small lump at the tube site for a week or two
- Tiredness, especially after time on a monitored unit
- Being started on or kept on blood-thinning medicine
- Needing further tests to find the cause of the clot
- A gradual rather than instant return to your usual activities
Aftercare
- Take blood-thinning medicine exactly as prescribed and do not stop without medical advice.
- Keep the tube site clean and dry, and watch it for swelling, bleeding or increasing pain.
- Be alert for signs of bleeding anywhere, such as black or bloody stools, blood in urine, coughing or vomiting blood, or unusual bruising.
- Attend all follow-up appointments and any planned repeat scans.
- Tell any dentist, pharmacist or other doctor that you are on blood thinners before treatment.
- Ask about wearing a compression stocking if you were treated for a leg-vein clot.
- Know who to contact urgently, day or night, if you have warning signs after discharge.
- Written information about your blood-thinning medicine and how long to take it
- A clear list of bleeding warning signs to watch for
- Your follow-up appointment and any repeat-scan dates
- A named contact and an out-of-hours number
- A note of why the clot is thought to have happened, if known
- Any compression stocking advice if relevant
- A list of medicines to avoid or check before starting
Scars and how they heal
There is usually no surgical scar. The tube goes in through a small puncture (often in the groin), which may bruise and leave a tiny mark. If a narrowing was treated with a stent, that stays inside the vessel and is not visible.
⚠ Get urgent help if…
- Sudden severe headache, weakness, numbness, slurred speech or confusion (possible bleeding in the brain) — call 999
- Heavy or uncontrolled bleeding from the tube site
- Vomiting blood, coughing up blood, or black, tarry or bloody stools
- Blood in your urine, or unusual heavy bruising
- A leg or other limb that becomes cold, pale, numb or very painful again
- Chest pain or sudden breathlessness
- Feeling faint, very dizzy or unusually drowsy
Who to contact: your clinician, clinic or test provider first (keep their number to hand). For urgent advice when you can't reach them, call NHS 111. In an emergency, call 999.
General guidance — it doesn't replace the specific advice your radiologist gives you.
Results & realistic expectations
A good result means the blocked vessel reopens and blood flow returns, which is checked with repeat scans. Sometimes the clot dissolves fully; sometimes only partly, and a further procedure or surgery is needed.
Even when the treatment works, it treats the clot, not the reason it formed. You will usually need ongoing blood thinners and tests to reduce the chance of another clot. Restoring blood flow quickly gives the best chance of saving tissue, but it cannot always reverse damage that has already happened.
Thrombolysis deals with one clot at one moment. It does not protect you from future clots, which is why the underlying cause matters and why blood-thinning medicine and follow-up are usually needed. How durable the result is depends on the cause and on whether any narrowing in the vessel was also treated.
Related tests, treatments or support
Thrombolysis is often combined with treating the cause of the blockage, such as opening a narrowed artery with a balloon or stent, or with a device that helps break up or remove the clot. In stroke care it may be paired with mechanical clot removal (thrombectomy). Blood-thinning medicine almost always continues afterwards.
Follow-up & long-term care
Follow-up usually includes a hospital review, repeat imaging of the treated vessel, and a plan for how long to stay on blood thinners. If the clot was unprovoked, you may be referred for tests to look for an underlying cause. Any longer-term effects, such as leg swelling after a vein clot, are also reviewed.
- Blood-thinning medicine, often for months or longer, with monitoring where needed
- Repeat scans to check the treated vessel
- Compression stockings after some leg-vein clots
- Review of risk factors such as blood pressure, smoking and any clotting tendency
Repeat, follow-on and what comes next
- Sometimes the clot does not fully dissolve and the infusion is extended, a clot-removal device is used, or surgery is needed.
- A narrowing that caused the clot may need treating with a balloon or stent at the same time.
- Repeat scans are normal to judge progress and decide next steps.
- Even a good early result does not prevent future clots, so ongoing treatment is usually needed.
Ask what happens if the result is unclear or needs repeating, and what is included if further tests or follow-up are needed.
What good aftercare looks like
- Close in-hospital monitoring during and after the infusion, with clear escalation if bleeding occurs.
- A written plan for blood-thinning medicine, including how long to take it.
- Clear, written bleeding warning signs and an urgent contact route after discharge.
- Arranged follow-up imaging and review of the underlying cause.
- Joined-up care between interventional radiology, the relevant specialty and your GP.
What affects the cost
Costs vary a great deal between people and providers, and we don't publish prices. What matters is understanding what drives the cost and making sure your quote is complete. The main things that affect it:
- This is emergency or urgent hospital treatment, so it is not a shoppable elective service and Vuemedics does not present a private quote pathway for it
- Where care is delivered privately as part of inpatient treatment, cost would reflect the interventional radiologist and team, imaging suite time and the clot-dissolving drug used
- Intensive or high-dependency monitoring during and after the infusion adds significantly to cost
- Any additional procedures, such as a balloon, stent or clot-removal device, add to cost
- Length of hospital stay and the investigations needed to find the cause affect the total
- Because this is urgent treatment, the focus should be on the clinical plan rather than a price comparison
- If care is private, written confirmation of who leads the treatment and where it is done
- Whether intensive or high-dependency monitoring is included
- Whether follow-up scans and review are included
- What happens, clinically and financially, if a further procedure or surgery is needed
- How ongoing blood-thinning medicine and follow-up will be arranged
On the NHS? Thrombolysis is almost always delivered as urgent NHS hospital care decided by the treating team; it is not a planned private self-pay treatment, and Vuemedics does not present it as one.
You're entitled to your total cost in writing — including reports, follow-up and what happens if the result is inconclusive — before you decide.
Consent traps and marketing red flags
These are not small details. They are often where patients lose choice, time to reflect, or realistic expectations.
Consent traps
- Not making clear that the main risk is bleeding, including the rare risk of bleeding in the brain.
- Giving the impression it cures the problem, rather than treating one clot.
- Not explaining that blood thinners alone or surgery may be reasonable alternatives.
- In an emergency, rushing through risks without checking the person (or family) has understood.
- Not setting out the plan if the clot does not clear or bleeding occurs.
Marketing red flags
- Any private clinic presenting clot-dissolving treatment as a routine, low-risk, shoppable service.
- Downplaying the bleeding risk or the need for intensive monitoring.
- Promising a clot will be fully dissolved or a limb fully saved.
- Suggesting it removes the need for blood thinners or further investigation.
Choosing a specialist safely
- Check the radiologist is on the GMC Specialist Register for this area.
- Make sure they work at a CQC-registered service, and look for membership of the relevant Royal College or professional body.
- You're entitled to time to consider and to have your questions answered before you agree — the radiologist who looks after you should explain it, not a salesperson.
- Be wary of pressure: time-limited offers or deposits taken before you've had time to think are red flags, not bargains.
- You're entitled to your total cost in writing — including any follow-up — before you decide.
Questions to ask your medical professional
Take this to your consultation. A good radiologist will welcome every one of these.
- Why is thrombolysis being recommended for me rather than blood thinners alone?
- What is my personal risk of serious bleeding, including bleeding in the brain?
- What is the plan if the clot does not dissolve, or if bleeding happens?
- Will I need surgery or a stent as well, and what would that involve?
- How long will I need blood thinners afterwards, and why?
- What tests will be done to find out why the clot formed?
- Are you on the GMC Specialist Register for this area, and which Royal College or professional body are you a member of?
- Will you be the radiologist who carries out my procedure, and who looks after me afterwards?
- What are the risks for someone like me, and how often do your own patients have a problem or need it repeated or redone?
- What does a realistic result look like — and what can this procedure not achieve?
- What are my options, including waiting, doing nothing for now, or choosing a different approach?
- Can I have written information, results and aftercare instructions in a format I can use, including any accessibility or communication support I need?
- What is the total cost in writing, including any follow-ups, and how much time do I have to decide?
Frequently asked questions
Is thrombolysis an emergency treatment?
What is the main risk?
Will it cure the problem?
Is this something I would arrange privately?
What happens if it does not work?
How long does it take?
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How we made this page
Medically reviewed by a GMC-registered consultant. Written in plain English, checked against NHS, NICE, GMC and relevant Royal College / specialist-society guidance, and kept under review. No clinic paid to appear on this page, and we publish no pricing. This is general information to help you prepare — it is not a substitute for advice from your own clinician. How we review our guides →
Source hierarchy: UK regulator and NHS/NICE guidance first, then relevant Royal College or specialist-society guidance, then peer-reviewed evidence for procedure-specific figures where available.
Sources & standards: BSIR — Thrombolysis patient leaflet NHS — DVT (deep vein thrombosis) NHS — Stroke treatment (thrombolysis) NHS — Pulmonary embolism NICE — Ultrasound-enhanced, catheter-directed thrombolysis for pulmonary embolism (IPG524) Catheter-directed thrombolysis vs anticoagulation in DVT — PMC review
Reviews reflect patients' experience of care, not clinical outcomes. For procedure volumes and outcome data see PHIN.
Last medically reviewed 2026-09-21. Spotted something wrong or out of date? Report an error in this guide.
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