Swelling in the Legs or Ankles (Peripheral Edema)

Peripheral edema is the accumulation of excess fluid in the interstitial spaces of the lower extremities — most commonly the ankles, feet, and lower legs — resulting in visible and palpable swelling. It can be unilateral (affecting one leg) or bilateral (affecting both legs), and ranges in severity from mild puffiness around the ankles that indents when pressed (pitting edema) to severe, tense swelling involving the entire lower leg and thigh.

While peripheral edema is a common and frequently benign finding — particularly bilateral ankle swelling related to prolonged standing, hot weather, or certain medications — unilateral or rapidly progressive lower extremity swelling, or edema in the context of known or suspected malignancy, warrants careful clinical evaluation.

• Lymphatic obstruction (lymphedema) from malignancy or treatment 
  
  
• Venous compression from pelvic or abdominal masses 
  
  
• Impaired renal function (bilateral ureteral obstruction) 
  
  
• Deep vein thrombosis (DVT) 
  
  
• Lymphocele after pelvic lymph node dissection 
  
  
• Systemic causes (heart, liver, kidney) 
  
  
• Medications 
  
  
• Prolonged immobility and gravitational edema 

See a physician if:

• Leg or ankle swelling is new, progressive, or unexplained
• Swelling is unilateral — single-leg swelling, particularly if accompanied by pain, warmth, and redness, suggests a deep vein thrombosis and requires urgent evaluation
• Swelling develops in the context of a known or suspected pelvic or abdominal malignancy
• Swelling follows pelvic surgery or pelvic lymph node dissection for urological cancer
• Leg swelling is accompanied by decreased urine output, which may indicate impaired renal function

Seek emergency evaluation immediately if:

• Sudden onset of severe leg pain and swelling occurs, particularly after prolonged immobility (travel, surgery, or hospitalization) — this presentation is consistent with deep vein thrombosis
• Leg swelling is accompanied by acute shortness of breath, chest pain, or coughing up blood — pulmonary embolism is a medical emergency
• Bilateral leg swelling develops rapidly in the context of known cancer with pelvic or abdominal involvement