• Clinical science



Edema is an abnormal accumulation of interstitial fluid caused by a variety of conditions, including, for instance, generalized fluid retention and localized reactions to trauma and allergies. Edema may manifest with swelling of the extremities (peripheral edema) or with internal fluid accumulation in organs and body cavities (e.g., pulmonary edema, pleural effusion). Patients with peripheral edema usually present with painless swelling of the lower legs. A residual indentation left by pressure on the site of the swelling indicates pitting edema. Bilateral lower limb pitting edema is often a sign of cardiac failure, while generalized peripheral pitting edema with swelling of the eyelids indicates hypoalbuminemia (e.g., in nephrotic syndrome). Nonpitting edema is seen especially in patients with lymphatic disorders and thyroid conditions.

General features



Pitting edema

  1. Fluid retention
  2. Protein deficiency; (mainly hypoalbuminemia) : nephrotic syndrome, liver cirrhosis, malnutrition, protein-losing enteropathy
  3. Hydrostatic: chronic venous insufficiency; , pregnancy, deep vein thrombosis, post-thrombotic syndrome
  4. Increased capillary permeability: inflammation, infections, toxins, burns, allergic reactions, trauma

Nonpitting edema

  • Lymphedema: due to lymphatic obstruction (see below)
  • Myxedema: hypothyreosis; (generalized), hyperthyreosis (typically pretibial)

Generalized vs. localized edema

Generalized Localized





  • Definition: edema associated with lymphatic obstruction and reduced fluid clearance due to compromised lymphatic vessels or lymph nodes
    • Lipid-rich, protein-rich fluid in the interstitial space that has high viscosity
  • Etiology
  • Clinical findings
  • Stages
    • Latent stage
    • Reversible swelling
    • Gradual fibrosis
    • Irreversible elephantiasis
  • Treatment
    • Conservative
      • Manual compression therapy and compression garments
      • Elevation of the involved limb
      • Exercise
      • Management of underlying disease
    • Surgical
      • Resection of lymphatic vessels
      • Lymphaticovenous anastomosis and lymphatic vessel grafting
      • Vascularized lymph node transfer

In lymphedema toes are affected, in contrast to venous edema.