Pathophysiology, diagnosis and treatment of ascites in cirrhosis.

The mechanism by which ascites develops in cirrhosis is multifactorial Severe sinusoidal portal hypertension and hepatic insufficiency are the initial factors. They lead to a circulatory dysfunction characterized by arterial vasodilation, arterial hypotension, high cardiac output and hypervolemia and to renal sodium and water retention. There are evidences that arterial vasodilation in cirrhosis occurs in the splanchnic circulation and is related to an increased synthesis of local vasodilators. Vascular resistance is normal or increased in the remaining major vascular territories (kidney, muscle and skin and brain). Splanchnic arterial vasodilation not only impairs systemic hemodynamics and renal function but also alters hemodynamics in the splanchnic microcirculation. The rapid and high inflow of arterial blood into the splanchnic microcirculation is the main factor increasing hydrostatic pressure in the splanchnic capillaries leading to an excessive production of splanchnic lymph over lymphatic return. Lymph leakage from the liver and other splanchnic organs is the mechanism of fluid accumulation in the abdominal cavity. Continuous renal sodium and water retention perpetuates ascites formation. Large volume paracentesis associated with albumin infusion is the treatment of choice of tense ascites because it is very effective and rapid and is associated with fewer complications that the traditional treatment (sodium restriction and diuretics). However, diuretic should be given after paracentesis to prevent reaccumulation of ascites. In patients with moderate ascites diuretics should be preferred as initial therapy. Patients with refractory ascites could be treated by paracentesis or percutaneous transjugular portacaval shunt (TIPS). TIPS is more effective in the long term control of ascites but may impair hepatic function and induce chronic hepatic encephalopathy.