Symptom

Swollen Ankles & Oedema: What's Causing the Fluid?

Pitting oedema — swelling that leaves a pit when pressed — is one of medicine's most common signs. The cause can range from trivial to life-threatening.

Pitting oedema
Fluid leaking into tissue
Most common cause
Venous insufficiency
Dangerous causes
Heart/kidney/liver failure
Testing
BNP, eGFR, albumin, ECG
Urgent AssessmentNew sudden-onset leg swelling — especially one leg, warm and red — may be deep vein thrombosis (DVT). Bilateral swelling with breathlessness suggests heart failure. Both need urgent assessment.

Causes by Pattern

PatternLikely Cause
One leg, warm, redDVT — urgent assessment
One leg, varicose veinsChronic venous insufficiency
Both legs, worse at end of dayVenous insufficiency, prolonged standing
Both legs + breathlessness + fatigueHeart failure
Both legs + facial puffiness + frothy urineNephrotic syndrome (kidney disease)
Both legs + jaundice + spider naeviLiver cirrhosis (low albumin)
Pitting oedema + hot jointsReactive arthritis
Elevate and MoveFor simple venous oedema, elevating legs above heart level for 30 minutes, 3–4 times a day, and walking regularly significantly reduces fluid accumulation.
Is ankle swelling at the end of the day normal?
Mild ankle swelling that resolves overnight after elevation is common, especially after long periods of standing or sitting. It's usually benign but worth mentioning to a GP if persistent.
Can heart failure cause swollen ankles?
Yes — bilateral ankle and leg oedema is a classic sign of right-sided heart failure. It's usually accompanied by breathlessness, fatigue, and raised jugular venous pressure.
What blood tests check for the cause of oedema?
Key tests: BNP or NT-proBNP (heart failure), eGFR + urine protein (kidney disease), albumin + LFTs (liver disease), TFTs (hypothyroidism causes non-pitting myxoedema).
How is DVT diagnosed?
Clinical assessment + D-dimer blood test. If D-dimer is raised or clinical suspicion is high, a Doppler ultrasound of the leg veins is performed — it's highly accurate.
Medical Disclaimer: This page is for general education only and does not replace professional medical advice. Always consult a qualified healthcare provider.