Ascites is 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 Oct;55 Suppl 6:vi1-12.
https://gut.bmj.com/content/55/suppl_6/vi1.long
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, computed tomography scan, or magnetic resonance imaging 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, hypo-albuminemia, 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 Feb 17;322(7283):416-8.
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 Apr 15;350(16):1646-54.
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 Feb 17;322(7283):416-8.
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 Dec;151(12):705-8.
http://www.ncbi.nlm.nih.gov/pubmed/23330265?tool=bestpractice.com
Other causes
Other causes of portal hypertension that may be associated with ascites include congestive heart failure, constrictive pericarditis, alcoholic liver disease, fulminant hepatitis, subacute hepatitis, massive liver metastasis, and Budd-Chiari syndrome.
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.
