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Health condition · Clinically reviewed

Leg ulcer, the causes, the assessment - and why compression heals most of them.

A chronic wound below the knee is not just a slow-healing scratch. It is a signal from the veins, arteries or skin that needs a proper assessment and a plan.

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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 for Cardiovascular and Vascular Care and NHS wound-care standards.

  • 03

    Current for 2026

    Reflects modern UK practice on ABPI, compression bandaging and specialist vascular referral.

Key facts

Leg ulcer at a glance.

The essentials, in plain English - what it is, the common types, and how it is assessed and treated in the UK today.

  • What it is

    A break in the skin below the knee that has failed to heal within four to six weeks - not a passing scratch, but a chronic wound with an underlying cause.

  • Most common cause

    Venous disease accounts for around seven in ten leg ulcers, driven by chronic venous insufficiency and varicose veins.

  • Second most common

    Arterial disease from peripheral arterial disease causes roughly one in five - painful, punched-out and needing specialist vascular review.

  • Foundation therapy

    Once arterial supply is confirmed safe by ABPI, graduated compression (typically four-layer bandaging) is the gold standard for venous ulcers.

  • Referral matters

    Mixed, arterial, diabetic, vasculitic and non-healing ulcers need a specialist commissioned tissue-viability and vascular pathway.

  • It can come back

    Recurrence is common without lifelong compression stockings and treatment of the underlying vein or artery problem.

Why this guide matters

Diagnose the cause, then heal the wound.

A leg ulcer is a symptom, not a diagnosis. The three points below shape everything else on this page.

  • ABPI before compression

    A hand-held Doppler ankle-brachial pressure index confirms the arterial supply. Compression is powerful but unsafe on an ischaemic leg.

  • Treat the vessels underneath

    Where duplex shows venous reflux or arterial stenosis, treating the vessel (ablation, angioplasty, bypass) cuts recurrence and speeds healing.

  • MDT for anything atypical

    Mixed, diabetic, vasculitic, malignant and non-healing ulcers need a specialist commissioned tissue-viability and vascular pathway.

How the diagnosis is made

From a wound below the knee to a clear plan.

The steps a UK GP, tissue-viability nurse or vascular surgeon will normally follow, in order - so you know what to expect and why.

  1. 01

    Assessing

    History and risk factors

    Duration of the ulcer, previous DVT, varicose veins, diabetes, smoking, claudication and rest pain all point towards a cause.

  2. 02

    Assessing

    Examine the leg

    Site, edge, base, exudate and surrounding skin. Haemosiderin staining and lipodermatosclerosis suggest venous disease; pale, cool, hairless skin suggests arterial.

  3. 03

    Assessing

    Check pedal pulses

    Absent or weak dorsalis pedis and posterior tibial pulses raise the suspicion of peripheral arterial disease and change management.

  4. 04

    Confirming

    ABPI (ankle-brachial index)

    A hand-held Doppler measurement: 0.8 to 1.3 is normal, below 0.8 suggests arterial disease, below 0.5 is critical limb ischaemia.

  5. 05

    Confirming

    Duplex ultrasound

    Specialist vascular imaging that maps venous reflux or arterial stenosis and guides definitive treatment of the underlying vessel.

  6. 06

    Confirming

    Wound swab and biopsy

    Not routine - reserved for suspected infection, atypical appearance or an ulcer failing to heal, when malignancy (Marjolin) must be excluded.

  7. 07

    Referring

    MDT referral

    Specialist commissioned tissue viability, vascular surgery and dermatology work together on mixed, complex or non-healing ulcers.

Typical timeline: a first assessment and ABPI within two weeks, and a settled plan shortly after.

Types and features

What a leg ulcer looks like.

Location, edge, base and the surrounding skin give away the underlying cause. And the features that mean it is time to escalate.

  • Venous ulcer - gaiter area

    Shallow, irregular edge, moderate exudate, sited above the medial malleolus with haemosiderin staining and lipodermatosclerosis.

  • Arterial ulcer - punched-out

    Deep, well-demarcated, painful ulcers on the toes, heel or shin with pale, cool, hairless surrounding skin.

  • Mixed ulcer

    Features of both venous and arterial disease - compression must be modified and specialist vascular input is essential.

  • Diabetic and neuropathic ulcer

    Plantar surface of the foot, often painless because of neuropathy - see also foot drop and diabetes type 2.

  • Pressure ulcer

    Over bony prominences (heel, malleolus) from sustained pressure - overlaps with decubitus ulcers and needs offloading.

  • Vasculitic ulcer

    Painful, purpuric, irregular ulcers on the lower leg - a feature of systemic vasculitis such as granulomatosis with polyangiitis.

  • Malignant ulcer (Marjolin)

    A long-standing ulcer with rolled or heaped edges that changes character - biopsy under specialist commissioned dermatology.

  • Red flag - critical limb ischaemia

    Rest pain, cold pale foot, absent pulses and rapidly enlarging ulcer - urgent same-day specialist vascular referral.

Treatment

How leg ulcer is treated in the UK.

Assess the vessels, compress the venous leg, revascularise the arterial leg, offload the diabetic foot - and dress the wound well throughout.

  • Graduated compression bandaging

    The gold standard for venous ulcers once ABPI is safe (typically 0.8 to 1.3). Four-layer bandaging supports the calf pump and heals most ulcers. See our compression bandaging service.

  • Varicose vein treatment

    Where duplex shows reflux, treating the underlying vein (endovenous ablation or foam sclerotherapy) reduces recurrence. See our varicose vein clinic.

  • Revascularisation

    For arterial or critical mixed ulcers - angioplasty or bypass restores blood supply under specialist commissioned vascular care. See lower limb angioplasty.

  • Wound care and debridement

    Specialist tissue-viability nurses select dressings, debride slough and manage exudate through the healing phases. See our wound care clinic.

  • Diabetic foot offloading

    Total-contact casting, bespoke footwear and pressure redistribution alongside optimised glucose control - see diabetes type 2.

  • Antibiotics for true infection

    Reserved for spreading cellulitis, systemic upset or biopsy-proven infection, guided by microbiology - not for routine bacterial colonisation.

  • Nutrition, pain and lifestyle

    Protein, vitamin C, zinc, smoking cessation and analgesia support healing. A dietitian can help where intake is poor.

  • Skin graft and tissue engineering

    For large or non-healing ulcers, split-thickness grafts or bioengineered skin substitutes under specialist commissioned plastic or vascular care.

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 GP or vascular team knows your leg and history and can tell you which parts apply to you. If in doubt, get seen.

  • NICE. Leg ulcer - venous: management (CKS).

  • NICE. Peripheral arterial disease: diagnosis and management (CG147).

  • National Wound Care Strategy Programme. Lower limb recommendations.

  • British Society for Cardiovascular and Vascular Care. Compression and vascular assessment standards.

Red flags

When a leg ulcer needs urgent attention.

Most leg ulcers are managed in community clinics. These are the situations that need same-day or specialist care.

  • Critical limb ischaemia

    Rest pain, cold pale foot, absent pulses or rapidly enlarging ulcer - urgent same-day specialist vascular referral.

  • Spreading cellulitis or sepsis

    Expanding erythema, fever, tachycardia or systemic upset - treat as an infection emergency, not a routine ulcer.

  • Suspected malignancy (Marjolin)

    Chronic ulcer with rolled or heaped edges, bleeding or change in character - biopsy under specialist commissioned dermatology.

  • Diabetic foot with deep ulcer

    Any diabetic foot ulcer probing to bone, with cellulitis, or in a patient systemically unwell needs the specialist diabetic foot team the same day.

  • Vasculitic features

    Painful, purpuric ulcers with joint, kidney or respiratory symptoms suggest systemic vasculitis - urgent rheumatology or renal opinion.

  • ABPI below 0.5

    Signals critical arterial disease - compression is unsafe and the leg needs urgent vascular assessment.

  • Non-healing at 12 weeks

    A venous ulcer that has not reduced meaningfully after three months of well-applied compression needs specialist tissue-viability and vascular review.

  • Recurrent DVT or sudden new leg swelling

    Consider deep vein thrombosis in any acute change - not simply another ulcer flare.

  • Charcot foot

    Warm, swollen, deformed diabetic foot with or without ulceration - urgent diabetic foot MDT referral.

Living with it

A treatable condition, with a clear ladder.

Four things that make the biggest difference day to day - compression stockings, skin care, calf-pump movement and knowing when to escalate.

A quiet reminder

Prevention is the second half of healing.

Once a leg ulcer has healed, wearing hosiery and treating the underlying vein or artery problem is what keeps the next one away.

  1. 01 Compression

    Wear the stockings

    Once the ulcer heals, lifelong graduated compression hosiery cuts recurrence by more than half. Get the class and fit right with a nurse.

  2. 02 Skin care

    Look after the surrounding skin

    Daily emollient, gentle cleansing and treating eczema early stops the next ulcer starting where the last one healed.

  3. 03 Movement

    Move the calf pump

    Ankle exercises, walking and leg elevation for part of each day help venous return - inactivity is the enemy of healing.

  4. 04 Escalate

    Don’t wait months

    Any wound below the knee that hasn’t healed at six weeks deserves a proper vascular assessment - not another dressing change.

Frequently asked

Everything we get asked about leg ulcer.

Quick answers on causes, ABPI, compression, healing time and recurrence.

  • What is a leg ulcer?

    A break in the skin below the knee that has failed to heal within four to six weeks. It is a symptom of an underlying problem - most commonly chronic venous insufficiency, but also peripheral arterial disease, diabetes, pressure, vasculitis or, rarely, skin cancer.

  • How is the cause worked out?

    Through a careful history, examination of the leg, pedal pulses and an ankle-brachial pressure index (ABPI) with a hand-held Doppler. Duplex ultrasound maps the veins or arteries, and biopsy is used selectively for atypical or non-healing ulcers.

  • Why does compression bandaging work?

    Graduated compression supports the calf muscle pump, reduces venous pressure and swelling, and improves oxygen delivery to the wound. Four-layer bandaging is the gold standard for venous ulcers once ABPI has confirmed the arterial supply is safe.

  • When is compression not safe?

    When the arterial supply is impaired - typically an ABPI below 0.8, and definitely below 0.5. In those cases the priority is a specialist vascular review to consider revascularisation before any compression is applied.

  • How long do leg ulcers take to heal?

    A well-managed venous ulcer often heals in 12 to 24 weeks with proper compression, though larger and older ulcers take longer. Arterial, diabetic and mixed ulcers are less predictable and need a specialist commissioned pathway.

  • Will it come back?

    Recurrence is common without lifelong compression stockings and treatment of the underlying vein or artery problem. Treating varicose vein reflux, wearing hosiery and looking after the skin all cut the risk substantially.

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