Ascites is defined as a pathological collection of fluid in the peritoneal cavity. The most common cause is cirrhosis, accounting for approximately 75% to 80% of cases.
[1]
Moore KP, Aithal GP. Guidelines on the management of ascites in cirrhosis. Gut. 2006;55:vi1-vi12.
http://www.ncbi.nlm.nih.gov/pubmed/16966752?tool=bestpractice.com
Clinical features
Patients present with abdominal distension; fluid may be detected on physical examination with shifting dullness. Ultrasound, CT scan, or MRI can confirm the diagnosis. In the majority of patients the history and examination will provide important clues as to the aetiology of ascites (e.g., signs of chronic liver disease or cardiac failure). Causes include diseases that lead to portal hypertension, hypoalbuminemia, and neoplasms.
Cirrhosis
In cirrhosis, ascites forms due to renal dysfunction and abnormalities in portal and splanchnic circulation. Sodium retention is a major factor in pathogenesis.
[2]
Krige JEJ, Beckingham IJ. Clinical review: ABC of disease of liver, pancreas and biliary system. Portal hypertension-2. Ascites, encephalopathy and other conditions. BMJ. 2001;322:416-418.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1119638/
http://www.ncbi.nlm.nih.gov/pubmed/11179165?tool=bestpractice.com
Splanchnic arterial vasodilatation (secondary to hepatic fibrosis) leads to increased lymph formation, activation of the renin angiotensin system and sympathetic nervous system, and release of antidiuretic hormone. This causes renal sodium and water retention. There is increased resistance to portal flow resulting in portal hypertension, collateral vein formation and shunting of blood to the systemic circulation.
[3]
Ginès P, Cardenas A., Arroyo V, et al. Management of cirrhosis and ascites. N Engl J Med. 2004;350:1646-1654.
http://www.ncbi.nlm.nih.gov/pubmed/15084697?tool=bestpractice.com
About 50% of patients with cirrhosis develop ascites within 10 years.
[2]
Krige JEJ, Beckingham IJ. Clinical review: ABC of disease of liver, pancreas and biliary system. Portal hypertension-2. Ascites, encephalopathy and other conditions. BMJ. 2001;322:416-418.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1119638/
http://www.ncbi.nlm.nih.gov/pubmed/11179165?tool=bestpractice.com
[4]
Sikuler E, Ackerman Z, Braun M, et al. Guidelines for diagnosis and management of cirrhotic ascites and its complications. The Israeli Association for the Study of the Liver [in Hebrew]. Harefuah. 2012;151:705-708;719.
http://www.ncbi.nlm.nih.gov/pubmed/23330265?tool=bestpractice.com
Other causes
Causes of portal hypertension other than cirrhosis include congestive heart failure, constrictive pericarditis, alcoholic hepatitis, fulminant hepatitis, subacute hepatitis, massive liver metastasis, and Budd-Chiari syndrome, which may be associated with ascites. Conditions causing hypo-albuminemia such as nephrotic syndrome and protein-losing enteropathy may result in ascites. Peritoneal diseases including infectious peritonitis and malignancies can also cause ascites.
