Oedema

DEFINITION: The accumulation of abnormal amounts of fluid in the interstitium or body cavities.

CAUSES:

Increased hydrostatic pressure
A. Impaired venous return
B. Arteriolar dilatation

Reduced oncotic pressure of plasma
A. Reduced intake
B. Increased loss
C. Decreased production

Sodium retention
A. Excessive salt intake with reduced renal function
B. Increased tubular reabsorption of sodium

Lymphatic obstruction
A. Inflammatory
B. Neoplastic
C. Post surgical
D. Post irradiation

PATHOGENESIS
Arterial end oncotic pressure venous end
35mmHg 25mmHg 15mmHg

MORPHOLOGY

Subcutaneous tissue- localised or generalised (anasarca)

Body cavities- hydrothorax or pleural effusion; hydropericardium or pericardial effusion; hydroperitoneum or ascites

Organs- pulmonary oedema, cerebral oedema; Both can be fatal.