Reasoning GP · Algorithm · 1-page summary
Ankle swelling — new presentation
For: adults with new unilateral or bilateral ankle or leg swelling in primary care. Not for: children; established leg ulcers (use the leg ulcers algorithm). Pregnancy from 20 weeks or after the birth: check BP and urine every time (block 2).
Core rule: unilateral versus bilateral splits the differential. A single hot, swollen calf is a DVT until excluded; symmetrical pitting oedema points to a systemic or drug cause. Always examine both legs together.
0Stop — call 999 now — before any history
- Sudden severe leg swelling with collapse, or a pale or mottled limb (phlegmasia cerulea dolens, ileofemoral DVT) → 999
- Unstable: haemodynamic instability, shock, suspected massive PE, acute pulmonary oedema, severe hypoxaemia → 999
- Acute severe unilateral leg pain or pallor (acute limb ischaemia) → 999
- Pregnant or recently delivered with seizure, collapse or instability (eclampsia, HELLP) → 999
1Triage by pattern — unilateral or bilateral, pitting or not
| Pattern | First move |
|---|---|
| Unilateral, hot, tender | Recent travel, surgery, immobility → DVT pathway Same-day |
| Unilateral + fever | Spreading erythema, lymphangitis → cellulitis Same-day; admit if septic |
| Bilateral + breathless | Orthopnoea, PND, raised JVP, crackles → suspected heart failure Same-day |
| Bilateral pitting, well | Drug review, urinalysis, BP; bloods by picture |
| Non-pitting | Lymphoedema, myxoedema (TSH), lipoedema (spares the feet) |
2Screen — one row is enough
- DVT (two-level Wells): ≥2 → leg-vein USS within 4 h, or D-dimer + interim anticoagulation + USS within 24 h. ≤1 → D-dimer within 4 h; positive → USS as above Same-day
- Pregnancy ≥20 weeks or postpartum: new BP ≥140/90, proteinuria, sudden swelling of face, hands or feet, headache, visual or epigastric symptoms — even with a normal BP → Same-day maternity
- Nephrotic: facial and ankle oedema, frothy urine, marked proteinuria → Same-day
- Liver: jaundice, new ascites → Same-day
- Cancer: unexplained lymphadenopathy or splenomegaly → consider Suspected cancer pathway (NG12). Unexplained unilateral swelling: examine abdomen, pelvis, groin and nodes; a mass follows its NG12 site pathway.
3Assess — targeted, not blanket
☐ BP, HR, RR, temperature, SpO₂, weight ☐ JVP, heart sounds, chest, abdomen (liver, ascites, spleen) ☐ Both legs: symmetry, pitting, skin, varicosities, pulses, capillary refill, Stemmer sign ☐ Urinalysis ☐ By picture: U&E, albumin + LFT, FBC, TSH, urine ACR/PCR
NT-proBNP if heart failure suspected: <400 ng/L makes it less likely, not excluded; 400–2000 → specialist and echo within 6 weeks; >2000 → within 2 weeks (NG106).
Avoid: Homan's sign; extensive tests after a recent CCB start with no heart-failure features — switch first.
4Classify — only if the screen is negative
- Venous insufficiency (commonest) — worse through the day, varicosities, haemosiderin, lipodermatosclerosis → compression once arterial supply assessed.
- Drug — onset after amlodipine/CCB, NSAID, steroid, gabapentinoid, glitazone, oestrogen, minoxidil → switch or review.
- Cardiac — orthopnoea, PND, raised JVP, crackles → NT-proBNP pathway, ECG.
- Renal / hepatic — proteinuria, low albumin; ascites, stigmata → ACR, eGFR, LFT, albumin, INR.
- Lymphoedema — foot dorsum involved, skin thickening; Stemmer supports, does not exclude → lymphoedema clinic. Hypothyroid — non-pitting → TSH.
- Uncertain — say so. Call it idiopathic only once venous, dependent and drug causes are excluded; review in 2–4 weeks.
5Treat today — doses: NICE/SPC, BNF, local formulary
- DVT confirmed: rivaroxaban 15 mg BD for 21 days then 20 mg OD with food, or apixaban 10 mg BD for 7 days then 5 mg BD; at least 3 months. Check CrCl (Cockcroft–Gault), weight, FBC, liver function, bleeding risk, interactions. Specialist: CrCl <15, active cancer, antiphospholipid syndrome, pregnancy.
- Congestion (cardiac, renal, hepatic): loop diuretic at the lowest effective dose per local protocol; U&E at 1 week if higher risk.
- Venous: compression only after pulses and arterial risk checked (ABPI or toe pressure where indicated); not in decompensated HF, acute DVT or severe PAD.
- Self-care: leg elevation, walking and ankle exercises, weight loss, skin care. No routine salt or fluid restriction in heart failure (NG106).
6Refer routinely
- Suspected or confirmed lymphoedema → lymphoedema clinic (diuretics do not treat it).
- Non-healing venous ulcer, severe varicosities, or arterial disease found before compression → vascular / local leg-ulcer pathway.
- Nephrology (NG203): KFRE >5%, ACR ≥70 mg/mmol, ACR >30 + haematuria, sustained eGFR fall; eGFR <30 not known to nephrology (local). Refractory oedema → HF/renal team.
7Never reassure by
- Amlodipine on the drug chart when the patient is breathless.
- A low NT-proBNP when suspicion remains (obesity, on HF drugs).
- A normal BP in a pregnant woman with pre-eclampsia symptoms.
- A negative Homan's or Stemmer sign.
- "Idiopathic" before venous, drug and dependent causes are excluded.
- "Lymphoedema" in a unilateral leg without examining abdomen, pelvis, groin and nodes.
8Safety-net — say it, then document it
999 “Call 999 for sudden severe breathlessness, chest pain, collapse, or a leg that suddenly becomes severely painful or pale.” Same-day “Contact us today if the swelling spreads quickly, one leg becomes painful and warm, you get new or worse breathlessness, a fever or spreading redness, your skin turns yellow or your tummy swells, or your weight rises past your heart-failure plan. If pregnant: sudden swelling of the face, hands or feet, a bad headache, vision problems, upper tummy pain or vomiting — call your maternity unit.”
Follow-up: swelling and weight at 2–4 weeks (resolution after a drug switch); DVT anticoagulation review at 3 months.
✓Safe to leave primary care only if — all five, documented
No block 0–2 row applies
Both legs examined: pitting, skin, pulses
Urinalysis and BP done (pregnancy: urine protein)
Drug review done; cause named or uncertainty stated
Review date set; safety-net given
Summary of the full Reasoning GP ankle swelling algorithm, which holds the detail, examination, investigations and evidence. Sources: NICE NG158, NG106, NG12 (updated April 2026), NG203, NG145; National Wound Care Strategy Programme; local DOAC guidance. Clinical reference — follow local pathways and check doses: NICE/SPC, BNF.