← Full leg ulcers algorithm
Reasoning GP · Diagnostic Compass · decision tree

Leg ulcers in adults1 PAGE

An ulcer below the knee: is the limb at risk, how urgent, and what type is it?
NICE CG168 · NG19 · NG12 (Apr 2026) · NG152 · NG141
SIGN 120 · National Wound Care Strategy 2025
Reviewed Oct 2026 · next review Apr 2027
Applies to: adults with an ulcer below the knee, face to face. No strong compression before ABPI in both legs; a normal or high ABPI does not exclude disease in diabetes or CKD.
Leg ulcer presents

Necrotising fasciitis: pain out of proportion, crepitus, bullae, dusky skin, shock · Acute limb ischaemia; rapidly progressive tissue loss; gangrene with spreading infection · Sepsis with confusion or haemodynamic compromise · Diabetic foot ulcer with sepsis, ischaemia, gangrene, deep abscess · Uncontrolled bleeding from varicose veins or ulcer

Emergency?
YES
999 · EMERGENCY ADMISSION
Remove any compression; keep an ischaemic limb warm, dependent, protected; do not elevate it. Bleeding: press firmly, raise the leg.
NO

Rest pain, tissue loss with cold pulseless foot, ABPI <0.5 → same-day vascular · Diabetic foot ulcer → foot service ≤1 working day; fever, ischaemia, bone infection, Charcot → hospital now · Fever, rigors, raised NEWS2 → admit; exposed bone → same day · Rolled edge, friable granulation, bleeding (SCC) → suspected cancer pathway or biopsy · Growing soft-tissue lump → urgent direct-access ultrasound · Violaceous undermined edge → urgent dermatology; purpura, livedo → urgent rheumatology

Same day or cancer pathway?
YES
SAME DAY · CANCER PATHWAY
Pyoderma: no debridement. Black eschar in a hypertensive diabetic: urgent specialist. Not healed at 12 weeks alone is not an NG12 criterion.
NO
Which type?
Venousmedial, better elevated
  1. ABPI 0.8–1.3: compression about 40 mmHg (trained).
  2. Simple dressing; eczema: steroid to skin only.
  3. Refer every venous ulcer to vascular.
Arterial, mixedtoes, worse elevated
  1. No strong compression; vascular review.
  2. ABPI 0.5–0.8: mild only per local pathway.
  3. High-intensity statin, antiplatelet, no smoking.
Neuropathicplantar, painless, callus
  1. Foot service ≤1 working day (NG19).
  2. No compression just for oedema.
  3. Offloading, footwear, glucose control.
Infected, otherredness, pus; immobile
  1. Infection: oral flucloxacillin (NG152); review 2–3 days.
  2. Odour or exudate alone is not infection.
  3. Pressure ulcer: pressure pathway; safeguarding?
EVERY PATIENT

ABPI and tests

  • ABPI both legs, supine, rested; >1.3 unreliable → toe pressure.
  • Pulses, monofilament; measure, dated photo with scale.
  • HbA1c, urinalysis, FBC, U&E, LFTs, lipids; CRP if infected; nicorandil?
  • Not routinely: swab (NG152); ANCA/ANA.

Safety-net · follow up

  • 999: pain far worse than wound, dusky or crackling skin, foot suddenly pale, cold or numb, bleeding will not stop.
  • Today: pain or numbness under bandage (remove it), spreading redness, pus, black areas, fever.
  • 4 weeks no progress → review; 12 weeks not healed → escalate, biopsy if atypical.
Never: Reassure by a venous-looking leg, palpable pulses, or high ABPI in diabetes or CKD · Call pain under compression "expected"; treat odour or a positive swab as infection · Accept a painless diabetic ulcer, or "granulation" at a chronic edge (SCC)
Reasoning GP · Leg ulcers in adults · decision tree · v1.0 · Oct 2026 · Full algorithm: gpreasoning.uk/tools/algorithms/leg-ulcers.htmlDecision support, not a substitute for clinical judgement. Check doses in the SPC and your local formulary.