🩺 Peripheral Oedema

Peripheral oedema is the accumulation of fluid in the interstitial space, usually appearing in the lower limbs due to gravity. It results from an imbalance in Starling forces: increased capillary hydrostatic pressure, decreased oncotic pressure, or increased capillary permeability. Diagnosis entails distinguishing between local (usually unilateral) and systemic (usually bilateral) causes. It is a hallmark sign of several chronic conditions including congestive heart failure and renal disease.

Determine if the swelling is unilateral or bilateral and the speed of onset. Acute unilateral swelling suggests DVT or cellulitis. Bilateral swelling with dyspnoea suggests heart failure. Check for risk factors for VTE (recent surgery, malignancy, immobility). Review medications (Amlodipine, NSAIDs, steroids). Ask about changes in urine output (nephrotic syndrome) or alcohol intake (liver cirrhosis). Enquire about abdominal bloating or yellowing of the skin.

Assess for pitting by applying firm pressure for at least 5 seconds over a bony prominence (e.g., medial malleolus). Note the extent (ankles, mid-calf, knees, sacrum). In unilateral cases, measure calf circumference (10cm below tibial tuberosity); a difference >3cm is significant. Look for features of chronic venous insufficiency: haemosiderin staining, venous eczema, and lipodermatosclerosis. Check JVP and perform abdominal palpation for ascites or hepatomegaly.

Bilateral: Heart Failure, Chronic Venous Insufficiency, Renal Failure (Nephrotic/Nephritic), Liver Cirrhosis, Medication-induced (CCBs). Unilateral: DVT, Cellulitis, Ruptured Baker's Cyst, Lymphoedema.

Sudden onset unilateral calf pain and swelling (DVT); associated chest pain or breathlessness (PE or HF); heavy proteinuria or 'frothy' urine (Nephrotic syndrome); rapid weight gain and decreased urine output.

FBC, U&Es, LFTs (for albumin and cirrhosis signs), and TFTs are standard. Urinalysis (proteinuria) is vital to screen for nephrotic syndrome. If heart failure is suspected, check NT-proBNP and order an Echocardiogram. For suspected DVT, calculate the Wells score and perform a D-dimer (if low probability) or a peripheral venous duplex ultrasound (if high probability or positive D-dimer). A Chest X-ray may show features of cardiomegaly or pulmonary congestion.

Unilateral limb swelling is DVT until proven otherwise. Bilateral swelling in the absence of heart or liver disease is often due to venous insufficiency or medications (CCBs). Pitting oedema is common in systemic disease, whereas non-pitting oedema (especially in the feet/toes) is characteristic of lymphoedema. In heart failure, oedema is dependent, moving from ankles to sacrum in bedbound patients. Check the albumin levels; low oncotic pressure is a common driver.

Covers cardiovascular (oedema) and renal sections of the MLA. Emphasises the Starling forces (hydrostatic vs oncotic pressure) and the systematic approach to investigating multi-organ failure. Includes the interpretation of D-dimer in the context of clinical probability.