From the Guidelines
Rapid accumulation of ascites is most commonly caused by portal hypertension, usually due to liver disease, with an accuracy of approximately 97% when the serum albumin ascites gradient (SAAG) is ≥ 1.1 g/dL 1.
Causes of Ascites
- Liver disease: such as cirrhosis, massive liver metastasis, and liver involvement in right heart failure
- Peritoneal carcinomatosis: cancer that has spread to the peritoneum
- Tuberculous peritonitis: a rare form of tuberculosis that affects the peritoneum
- Heart failure: can cause ascites due to fluid overload
- Nephrotic syndrome: a kidney disorder that can cause fluid retention
- Pancreatic ascites: a rare condition where fluid accumulates in the abdomen due to a pancreatic disorder
Diagnostic Approach
The SAAG is a useful diagnostic tool to differentiate between portal hypertension and non-portal hypertension causes of ascites 1.
- A SAAG ≥ 1.1 g/dL suggests portal hypertension, while a SAAG < 1.1 g/dL suggests other causes of ascites.
- Additional tests, such as ascitic fluid analysis, cytology, and culture, may be necessary to determine the underlying cause of ascites 1.
Clinical Considerations
In patients with cirrhosis, ascites can be graded according to the amount of fluid accumulated in the abdominal cavity, and treatment should be tailored to the individual patient's needs 1.
- Dietary sodium restriction and diuretic therapy are the mainstays of treatment for patients with cirrhosis and ascites.
- Patients with non-portal hypertension-related ascites may require treatment of the underlying disorder, such as cancer or heart failure.
From the Research
Causes of Rapid Accumulation of Ascites
The rapid accumulation of ascites can be caused by various factors, including:
- Portal hypertension, which is the most common cause of ascites 2, 3, 4
- Sodium and fluid retention, which are key factors in the pathophysiology of ascites 2, 4
- Peripheral arterial vasodilatation hypothesis, which is the most accepted mechanism for inappropriate sodium retention and formation of ascites 2, 4
- Hepatic, renal, and cardiac disorders, which are the most common causes of ascites in children 2
- Liver cirrhosis, which is the most frequent cause of ascites 4, 5
- Malignant neoplasia, tuberculous infection, and cardiac insufficiency, which are also common causes of ascites 6
Pathophysiology of Ascites
The pathophysiology of ascites involves:
- Increased hydrostatic pressure at the sinusoidal level due to portal hypertension 4
- Alterations of splanchnic and systemic haemodynamics, including increased splanchnic inflow, reduced systemic resistance, and increased plasma volume and cardiac output 4
- Activation of antinatriuretic factors and sodium retention, which occurs in the setting of increased RAA system and SNS activity 4
- Overall activation of the renal prostaglandin system, which probably acts to maintain renal haemodynamics and GFR by counteracting the vasoconstricting effects of AII and noradrenaline on renal circulation 4
Diagnostic Approach
The diagnostic approach to ascites includes:
- Abdominal paracentesis with appropriate ascitic fluid analysis, which is probably the most cost-effective method of determining the cause of ascites 6
- Serum-ascites albumin gradient (SAAG), total protein concentration, cell count, and differential, which are routine ascitic fluid analysis parameters 6
- Optional ascitic fluid analysis, including cholesterol, fluid culture, cytology, tumor markers, lactate dehydrogenase, adenosine deaminase (ADA), triglyceride, amylase, glucose, brain natriuretic peptide (BNP), etc. 6