Ascites is a pathological collection of fluid in the peritoneal cavity. The most common cause is cirrhosis, accounting for approximately 75% of cases.[1]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
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, 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-albuminaemia, and neoplasms.
Cirrhosis
In 2017, cirrhosis caused more than 1.32 million deaths globally, compared with fewer than 899,000 deaths in 1990. Deaths due to cirrhosis constituted 2.4% of total deaths globally in 2017 compared with 1.9% in 1990.[2]GBD 2017 Cirrhosis Collaborators. The global, regional, and national burden of cirrhosis by cause in 195 countries and territories, 1990-2017: a systematic analysis for the Global Burden of Disease Study 2017. Lancet Gastroenterol Hepatol. 2020 Mar;5(3):245-66.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7026710
http://www.ncbi.nlm.nih.gov/pubmed/31981519?tool=bestpractice.com
In cirrhosis, ascites forms due to renal dysfunction and abnormalities in portal and splanchnic circulation. Sodium retention is a major factor in pathogenesis.[1]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.[1]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-albuminaemia such as nephrotic syndrome and protein-losing enteropathy may result in ascites. Peritoneal diseases including infectious peritonitis and malignancies can also cause ascites.
