07/06/2026
In pedal edema, pressing with a thumb for 10 seconds leaves a very deep pit (indentation)
"Why do patients who stay in bed for prolonged periods develop pedal edema (swelling of the feet)?"
Low gravity (Dependent position)
“low gravity” or “dependent position” refers to a body position in which a part of the body is positioned lower than the heart level, causing that area to be primarily affected by gravitational force.
Due to gravity, blood and interstitial fluid tend to accumulate in the dependent (lower) parts of the body, especially the lower limbs, leading to venous pooling and edema formation.
Causes of Pedal Edema
• Anemia:
A condition characterized by reduced red blood cell count or hemoglobin level, leading to decreased oxygen delivery to tissues. Severe or chronic anemia may contribute to tissue hypoxia and fluid imbalance.
• Low Hemoglobin (Hypohemoglobinemia):
A reduction in hemoglobin concentration in the blood, resulting in impaired oxygen-carrying capacity and potential tissue hypoxia, which may contribute indirectly to edema formation.
• Hypoproteinemia:
A decrease in total plasma protein levels in the blood, leading to reduced plasma oncotic pressure. This causes fluid to shift from the intravascular space into the interstitial tissues, resulting in edema.
• Hypoalbuminemia:
A specific form of hypoproteinemia characterized by low serum albumin levels. Since albumin is the main contributor to plasma oncotic pressure, its reduction leads to fluid leakage into interstitial spaces, commonly causing dependent edema such as pedal edema.
• Malabsorption Syndrome –
• Malabsorption syndrome is a clinical condition in which the small intestine is unable to properly absorb nutrients from food, including proteins, fats, carbohydrates, vitamins, and minerals.
• Although digestion may occur normally, the absorption of nutrients into the bloodstream is impaired, leading to nutritional deficiencies. This condition may result in weight loss, chronic diarrhea, weakness, and edema due to associated protein deficiency.
• Fluid Retention –
• Fluid retention is a condition in which the body accumulates excess fluid due to an imbalance in fluid regulation or impaired excretion. This occurs when the kidneys or circulatory system fail to eliminate fluid properly, leading to abnormal fluid accumulation in the interstitial spaces.
• Clinically, fluid retention commonly results in edema, particularly in dependent areas such as the lower limbs, ankles, and feet.
• In a patient with elevated urine creatinine, uremia, and acute renal failure (acute kidney injury), the kidneys lose their ability to properly filter and excrete waste products and excess fluid. As a result, there is accumulation of uremic toxins and fluid retention in the body.
• This condition leads to impaired renal excretory function with progressive fluid overload, which clinically manifests as generalized edema, including peripheral (pedal) edema.
Liver disease, liver failure, and ascites (accumulation of fluid in the abdomen) can lead to pedal edema (swelling of the feet).
This occurs due to the following mechanisms:
• In liver disease, the production of albumin is reduced
• Low albumin leads to a decrease in plasma oncotic pressure
• As a result, fluid leaks out of blood vessels into the interstitial tissues and accumulates in the abdominal cavity (ascites)
• Additionally, there is increased fluid retention in the body
Outcome:
Due to ascites and generalized fluid accumulation, swelling develops in the lower limbs and ankles, known as pedal edema.
If a patient remains lying on the same side (same position) for a long time and is unable to change position regularly, this can also contribute to pedal edema (swelling of the feet).
This occurs because:
• Prolonged immobility leads to reduced blood circulation in dependent areas
• Blood and fluid start to pool in the lower parts of the body (venous pooling)
• Lymphatic drainage becomes impaired
• Reduced muscle pump activity further decreases venous return
Outcome:
These factors together cause fluid accumulation in the lower limbs, resulting in pedal edema (swelling of the feet and ankles).
