# Follow the edema: from the leg to the urine

Follow the anatomical assessment sequence: leg interstitium and lymphatics; leg and thigh veins; pelvic veins and abdominal IVC; right heart, lungs and left heart; kidney filtration and tubules; ureters, bladder and urethra. This is an evaluation map, not a literal claim that tissue fluid is normally reabsorbed into local leg veins. Most filtered tissue fluid returns through lymphatics to central veins. Leg venous blood travels through the iliac veins and IVC, not through the portal liver in series.

Look for medication-related edema, inflammation and lymphatic failure; chronic venous insufficiency, DVT or proximal venous obstruction; cirrhosis with portal hypertension, reduced albumin and arterial underfilling; right or left heart failure; kidney disease and sodium retention; impaired diuretic delivery or response; and urinary obstruction including neurogenic bladder. Amlodipine can redistribute fluid into tissues; NSAIDs and thiazolidinediones can promote sodium retention. Match treatment to mechanism.

Assess onset, one leg versus both, pain, skin changes and medication timing. Suspected acute DVT needs prompt clinical assessment and an appropriate diagnostic pathway, often venous duplex; dyspnea or chest pain raises concern for pulmonary embolism. For chronic venous insufficiency, consider elevation, mobility and appropriately selected compression after vascular assessment. Diuretics for isolated venous edema without systemic volume overload can deplete the circulation and cause AKI. Venous disease and systemic congestion can coexist, so reassess rather than treating edema or creatinine alone.

[Levick and Michel, revised Starling principle — PubMed](https://pubmed.ncbi.nlm.nih.gov/20200043/) · [Ellison, 2019 — PubMed](https://pubmed.ncbi.nlm.nih.gov/30936153/)

Andrew Bland, MD, FACP, FAAP