Definition of Anasarca
Anasarca is severe, generalized edema characterized by widespread fluid accumulation throughout the interstitial spaces of the body, affecting the skin and soft tissues diffusely rather than being localized to dependent areas. 1
Clinical Characteristics
Anasarca represents the most extreme form of edema, progressing beyond localized swelling to involve the entire body, including the trunk, extremities, and potentially causing pulmonary edema and ascites 2
The condition manifests as widespread swelling of the skin due to massive effusion of fluid into the extracellular space, causing significant pain, discomfort, and functional impairment 3
Primary Pathophysiologic Mechanisms
Anasarca develops through two fundamental mechanisms that may occur independently or simultaneously:
Increased intravascular hydrostatic pressure - forcing fluid out of blood vessels into tissues 1
Decreased plasma oncotic pressure - reducing the force that normally keeps fluid within blood vessels, most commonly from severe hypoalbuminemia 1
Major Underlying Causes
Cardiac Etiologies
Acute and chronic heart failure is a leading cause, resulting from sodium and water retention due to reduced cardiac output and neurohormonal activation of the renin-angiotensin-aldosterone system 1
The fluid retention reflects congestion from elevated filling pressures, though peripheral edema may not always correlate with intravascular volume status 1
Renal Etiologies
Nephrotic syndrome is characterized by severe proteinuria, hypoalbuminemia, and anasarca as the predominant clinical manifestation 1
Approximately 70% of patients with AL amyloidosis develop renal involvement presenting with nephrotic syndrome and anasarca 1
Renal failure from any cause can lead to anasarca through impaired sodium and water excretion, particularly when combined with hypoalbuminemia 1
Hepatic Etiologies
- Liver cirrhosis produces anasarca through multiple mechanisms including decreased albumin synthesis, portal hypertension, and secondary hyperaldosteronism 1
Other Important Causes
Systemic vasculitides including granulomatosis with polyangiitis and eosinophilic granulomatosis with polyangiitis can cause renal involvement leading to anasarca 1
Malignant lymphoproliferative diseases may present with anasarca, likely mediated by tumor necrosis factor alpha (TNF-alpha) causing vascular leakage 4, 5
Critical Diagnostic Distinctions
Elevated jugular venous pressure improves the specificity of edema as a sign of cardiac congestion rather than other causes of fluid shifts 1
Anasarca may reflect extravascular volume shifts from low plasma oncotic pressure or high vascular permeability rather than elevated filling pressures, requiring assessment of multiple parameters including JVP 1
Pre-existing edema from non-cardiac causes (hepatic, renal, venous insufficiency) should be documented to avoid misattributing chronic edema to acute cardiac decompensation 1