Cirrhotic ascites. Pathophysiology, diagnosis, and management.

Cirrhotic ascites occurs via both overflow and underfill mechanisms. Intrahepatic hypertension activates a hepatic baroreceptor reflex that enhances renal sodium absorption; plasma volume is expanded. As cirrhosis progresses, the hepatoportal Starling forces become sufficiently disturbed to sequester this "overflow" in the peritoneal cavity, which results in ascites formation. "Underfill" of the vascular system occurs and eventually dominates the clinical picture. Finally, intrahepatic hypertension also activates the renin-angiotensin system, which causes renal vasoconstriction; the increase in renal prostaglandin synthesis maintains renal blood flow. Although cirrhotic ascites is traditionally classified as a transudate, the serum-ascites albumin gradient may be a better indicator of ascites secondary to portal hypertension than other causes. General management of patients with cirrhotic ascites includes severe restriction of dietary sodium intake and bed rest; diuretics are added if spontaneous diuresis does not occur after 3 to 4 days.