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Health condition · Clinically reviewed

Arteriovenous malformation, grading, ARUBA and modern multimodal care.

A congenital tangle of vessels that can sit silently for decades or present with sudden haemorrhage. The right imaging, the right MDT and the right modality change outcomes.

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A radiographer guides a patient onto the bed of an advanced 3 Tesla MRI scanner in a London imaging suite

Why trust this guide

  • 01

    Clinically reviewed

    Written by our editorial team and reviewed by a registered UK clinician before publication.

  • 02

    Sourced from guidance

    Checked against NICE, the British Society of Neuroradiologists, ARUBA and the international HHT guidelines.

  • 03

    Current for 2026

    Reflects modern UK practice including Spetzler-Martin grading, ARUBA-informed decision making and HHT cascade screening.

Key facts

AVM at a glance.

The essentials, in plain English - what an AVM is, where they arise, how they are graded and how they are treated in the UK today.

  • What it is

    A congenital tangle of abnormal arteries and veins that bypasses the normal capillary bed, producing a high-flow shunt.

  • Where they arise

    Cerebral, spinal, pulmonary, hepatic, uterine, vertebral and facial or cutaneous locations. Around 40 per cent of presentations are cerebral.

  • Cerebral risk

    Rupture risk is roughly 2 to 4 per cent per year. About half of cerebral AVMs first present with intracerebral haemorrhage. Mean age at presentation is in the thirties.

  • HHT link

    Pulmonary and hepatic AVMs cluster in hereditary haemorrhagic telangiectasia (Osler-Weber-Rendu), driven by ENG, ACVRL1 or SMAD4 mutations.

  • Grading

    Cerebral AVMs are graded Spetzler-Martin I to V using size, eloquence of adjacent brain and pattern of venous drainage.

  • Modern management

    Microsurgery, stereotactic radiosurgery and endovascular embolisation, alone or combined. The ARUBA trial reshaped how unruptured cerebral AVMs are considered.

Why this guide matters

One label, many locations, very different plans.

A cerebral AVM, a pulmonary AVM and a uterine AVM demand very different specialists and modalities. The three points below shape everything else on this page.

  • Location changes everything

    Brain, spine, lung, liver, uterus - each location has its own presentation, imaging pathway and treatment ladder.

  • HHT ties them together

    Pulmonary and hepatic AVMs cluster in HHT. One case in a family should trigger cascade genetic testing and organ screening.

  • MDT decisions beat single opinions

    Modern AVM care is decided by a joint neurosurgery, interventional neuroradiology and radiosurgery meeting - not a single specialist.

How the diagnosis is made

From first symptom to a graded plan.

The steps a UK neurology or neurovascular team will normally follow, in order - so you know what to expect and why.

  1. 01

    Assessing

    History and neurological exam

    Headache, seizure, focal deficit, myelopathy, epistaxis or unexplained hypoxia all point to a possible AVM in a different location.

  2. 02

    Assessing

    MRI brain or spine

    The first-line non-invasive study for suspected cerebral or spinal AVM. Shows the nidus, prior bleeds and adjacent eloquent tissue.

  3. 03

    Assessing

    MRA and CTA

    Magnetic resonance angiography and CT angiography map the feeding arteries, nidus size and draining veins before invasive imaging.

  4. 04

    Confirming

    Digital subtraction angiography

    DSA is the gold standard for cerebral AVMs. It confirms angioarchitecture and drives Spetzler-Martin grading (size, eloquence, venous drainage).

  5. 05

    Confirming

    HHT screening

    Contrast (bubble) echocardiogram and CT chest look for pulmonary AVMs. Liver Doppler and MRI assess hepatic involvement in suspected HHT.

  6. 06

    Preparing

    Genetic testing

    HHT gene panel covering ENG (HHT1), ACVRL1 (HHT2) and SMAD4 (juvenile polyposis-HHT overlap), with cascade testing offered to first-degree relatives.

  7. 07

    Preparing

    Neurovascular MDT

    A joint neurosurgery, interventional neuroradiology and radiation oncology meeting agrees the safest single-modality or multimodal plan.

Typical timeline: a first symptom to a graded, MDT-agreed plan in a few weeks.

Symptoms

How AVMs actually present.

Silent for decades in many patients, then a sudden bleed, seizure, focal deficit or shunt-related symptom. And the features that mean it is time to escalate.

  • Intracerebral haemorrhage

    Sudden severe headache, collapse or focal deficit. Around half of cerebral AVMs are found only when they bleed.

  • New-onset seizures

    Focal or generalised seizures, often in a young adult, without another obvious cause.

  • Focal neurological deficit

    Weakness, sensory change, speech disturbance or visual field loss depending on the AVM location.

  • Progressive myelopathy

    Leg weakness, sensory level, bladder disturbance and gait change point to a spinal AVM or dural fistula.

  • Hypoxia and paradoxical stroke

    Pulmonary AVMs produce a right-to-left shunt with exertional breathlessness, low oxygen levels, stroke or brain abscess.

  • Epistaxis and telangiectasia

    Recurrent nosebleeds and telangiectases on the lips, tongue and fingertips are the fingerprint of HHT.

  • High-output cardiac failure

    Breathlessness, ankle swelling and a hyperdynamic circulation may point to a hepatic AVM shunting large volumes of blood.

  • Red flag - thunderclap headache

    A sudden severe worst-ever headache needs urgent imaging to exclude AVM rupture or subarachnoid haemorrhage.

Treatment

How AVMs are treated in the UK.

Microsurgery, radiosurgery and endovascular embolisation for cerebral AVMs. Coil embolisation for pulmonary, bevacizumab for hepatic and UAE for uterine AVMs.

  • Microsurgical resection

    The definitive option for accessible low-grade cerebral AVMs (Spetzler-Martin I and II). Removes the nidus in one operation.

  • Stereotactic radiosurgery

    Gamma Knife or CyberKnife delivers a focused dose to small deep AVMs. Obliteration typically takes 2 to 3 years. See our /treatments/gamma-knife-radiosurgery/ guide.

  • Endovascular embolisation

    Onyx, coils or n-BCA glue delivered through a microcatheter. Used alone or as an adjunct to surgery or radiosurgery. See /treatments/cerebral-aneurysm-coiling/.

  • Combined multimodal therapy

    Large or complex AVMs are staged with embolisation to shrink the nidus before microsurgery or radiosurgery.

  • Pulmonary AVM embolisation

    Coil or plug embolisation of feeding arteries greater than 3 mm reduces stroke, brain abscess and hypoxia risk in HHT.

  • Bevacizumab for hepatic AVM

    Systemic anti-VEGF therapy reduces high-output cardiac failure and arteriovenous shunting. Liver transplant is reserved for refractory disease.

  • Uterine artery embolisation

    Bilateral UAE is the treatment of choice for uterine AVMs presenting with post-partum or post-D&C menorrhagia, and preserves fertility where possible.

  • HHT cascade care

    Genetic counselling, family cascade testing, annual surveillance, iron replacement for chronic epistaxis, nasal laser and septodermoplasty for severe bleeding.

Ruptured vs unruptured

Timing and ARUBA.

Ruptured cerebral AVMs are usually treated within 3 to 6 months to reduce re-rupture risk, which is highest in the first year. For unruptured cerebral AVMs, the ARUBA trial showed medical management was non-inferior to intervention over 5 years, so treatment is individualised in an MDT rather than automatic.

What this guide is based on

The sources behind every claim on this page.

UK national guidance, landmark trials and specialist society standards, current at the time of last review.

Key references

Guidelines and trials we relied on.

A quiet reminder

This guide is for information, not medical advice.

Your neurologist, neurosurgeon or interventional neuroradiologist knows your imaging and history and can tell you which parts apply to you. If in doubt, get seen.

  • ARUBA investigators. A randomised trial of unruptured brain arteriovenous malformations. The Lancet, 2014.

  • Spetzler RF, Martin NA. A proposed grading system for arteriovenous malformations. Journal of Neurosurgery.

  • Faughnan ME et al. Second international guidelines for the diagnosis and management of HHT. Annals of Internal Medicine.

  • NICE. Interventional procedures guidance on stereotactic radiosurgery for cerebral AVM (IPG211) and embolisation of AVMs.

  • British Society of Neuroradiologists. Standards for cerebral angiography and neurovascular MDT working.

Red flags

When AVMs need urgent attention.

Some presentations cannot wait for an outpatient clinic. These are the situations that need same-day imaging or emergency review.

  • Thunderclap headache

    Sudden severe worst-ever headache needs immediate emergency assessment and CT imaging to exclude AVM or aneurysm rupture.

  • First seizure

    Any first seizure in adulthood warrants urgent neurology review and brain imaging to look for a structural cause including AVM.

  • Focal neurological deficit

    New weakness, speech disturbance or sensory change is a stroke-pathway presentation. Call 999 and treat as a suspected stroke.

  • Progressive leg weakness or bladder change

    Suggests a spinal AVM or dural arteriovenous fistula. Needs urgent spinal MRI to avoid permanent cord damage.

  • Cyanosis or paradoxical stroke

    Unexplained low oxygen levels, stroke or brain abscess in a young patient can indicate a pulmonary AVM. Contrast echocardiogram is diagnostic.

  • Recurrent nosebleeds and family history

    Suggests HHT. A single case in a family should prompt cascade genetic testing and screening for pulmonary and hepatic AVMs.

  • Post-partum heavy bleeding

    Post-partum or post-D&C menorrhagia that does not settle deserves pelvic ultrasound with Doppler to exclude a uterine AVM.

  • Rupture within 12 months

    A ruptured cerebral AVM has the highest re-rupture risk in the first year. Treatment is usually offered within 3 to 6 months.

  • HHT with pregnancy

    Pulmonary AVMs can enlarge and bleed during pregnancy. HHT patients should be screened before conception where possible.

Living with it

A vascular anomaly, with a modern toolkit.

Four things that make the biggest difference for AVM patients and their families - an MDT plan, an honest read of ARUBA, HHT screening and realistic expectations of radiosurgery.

A quiet reminder

The right modality matters more than the fastest one.

A slower plan agreed by an experienced neurovascular MDT usually beats a quicker plan chosen in isolation.

  1. 01 MDT

    Insist on a neurovascular MDT

    AVM decisions are rarely one-modality. A joint neurosurgery, interventional neuroradiology and radiosurgery meeting produces the safest plan.

  2. 02 ARUBA

    Understand the ARUBA debate

    For unruptured cerebral AVMs, ARUBA showed medical management was non-inferior to intervention over 5 years. Decisions are individualised.

  3. 03 Screening

    Screen for HHT if it runs in the family

    One case in a family should prompt cascade genetic testing and pulmonary AVM screening even in asymptomatic relatives.

  4. 04 Recovery

    Give radiosurgery time

    Gamma Knife and CyberKnife take 2 to 3 years to obliterate an AVM. Interval MRI and angiography track progress.

Frequently asked

Everything we get asked about AVMs.

Quick answers on rupture risk, grading, ARUBA, HHT and pulmonary AVM treatment.

  • What is an arteriovenous malformation?

    An AVM is a congenital tangle of abnormal arteries and veins that bypasses the normal capillary bed. Blood shunts directly from the arterial to the venous side under high pressure, which is why AVMs can bleed, cause seizures or produce shunt-related symptoms depending on where they sit.

  • What is the risk of a cerebral AVM bleeding?

    The annual rupture risk for a cerebral AVM is roughly 2 to 4 per cent per year, and about half of cerebral AVMs are only discovered when they bleed. The risk is higher for AVMs that have already bled, have deep venous drainage or are associated with intranidal aneurysms.

  • What did the ARUBA trial change?

    The 2014 ARUBA trial randomised patients with unruptured cerebral AVMs to medical management or intervention. Over 5 years, medical management was non-inferior for stroke and death. The trial remains debated, but it means unruptured AVMs are now assessed case by case rather than automatically treated.

  • How is a cerebral AVM graded?

    The Spetzler-Martin scale grades cerebral AVMs from I to V using three features: size (small, medium or large), eloquence of the adjacent brain and pattern of venous drainage (superficial or deep). Low-grade AVMs are usually amenable to microsurgery, high-grade AVMs are more often managed with radiosurgery or embolisation.

  • What is HHT and how is it linked to AVMs?

    Hereditary haemorrhagic telangiectasia (Osler-Weber-Rendu) is an autosomal dominant condition caused by ENG (HHT1), ACVRL1 (HHT2) or SMAD4 mutations. It produces recurrent epistaxis, mucocutaneous telangiectases and visceral AVMs, especially in the lungs, liver and brain. Cascade testing and screening changes outcomes.

  • How are pulmonary AVMs treated?

    Pulmonary AVMs with feeding arteries greater than 3 mm are treated with transcatheter coil or plug embolisation. This reduces the right-to-left shunt and the risks of paradoxical stroke, brain abscess and hypoxia. Antibiotic prophylaxis for dental and surgical procedures is advised for HHT patients even after embolisation.

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