Edema - classification, etiology, pathogenesis, and clinical manifestations.
Edema is an excess accumulation of fluid in the interstitial tissue spaces, leading to visible swelling.
Classification
- 1 According to distribution
- 2 According to mechanism
Etiology
Hydrostatic edema
- Congestive heart failure (right-sided → systemic edema; left-sided → pulmonary edema).
- Deep vein thrombosis (localized).
Oncotic ( hypoproteinemic ) edema
- Nephrotic syndrome (protein loss in urine).
- Liver cirrhosis (decreased albumin synthesis).
- Malnutrition (protein deficiency).
- Protein-losing enteropathy.
Lymphatic edema
- Filariasis (parasite-induced lymphatic obstruction).
- Post-surgical lymph node removal (e.g., after mastectomy).
- Radiation-induced fibrosis.
Permeability edema
- Inflammation (release of histamine, bradykinin → increased permeability).
- Severe burns.
- Allergic reactions.
Pathogenesis
- 1 Starling forces imbalance
- Normally, fluid filtration from capillaries is balanced by reabsorption and lymphatic drainage.
- Edema occurs when filtration exceeds reabsorption and drainage.
- 2 Mechanisms
- Increased hydrostatic pressure → more fluid pushed out (e.g., heart failure).
- Decreased oncotic pressure → less fluid reabsorbed (e.g., hypoalbuminemia).
- Increased vascular permeability → proteins and fluid leak out (e.g., inflammation).
- Lymphatic obstruction → impaired drainage (e.g., filariasis).