[The physiopathology of ascites]

Sodium and water retention is constant in decompensated cirrhosis with ascites and edema. Sodium retention is due to several factors. Renal hemodynamic disturbances appear first: decrease in glomerular filtration and renal plasmatic perfusion, redistribution of renal perfusion to the juxtamedullar area where the longer nephrons reabsorb more sodium. Metabolic disorders of estrogens, natriuretic hormonal factor, prostaglandins and the kallikrein-kinin system contribute to greater sodium retention. Water retention is secondary to greater sodium reabsorption and to hyperactivity of the antidiuretic hormone. Sodium and water retention, associated with portal hypertension, with reduced oncotic pressure and with dynamic lymphatic insufficiency, is responsible for the production of ascites. The latter results in a decrease in the effective plasmatic volume, with non-suppression of the renin-angiotensin system, increased aldosterone production and additional sodium retention.