Causes of ascites can be categorised into portal and non-portal hypertension-related processes using an algorithm based on the history, physical examination and serum-to-ascites albumin gradient. This allows a focused approach to further investigation.
- Portal hypertension due to cirrhosis is the most common cause of ascites in western countries, accounting for about 80% of cases.
- Peritoneal malignancies and right heart failure account for most of the remaining cases.
- The serum-to-ascites albumin gradient correctly differentiates patients with ascites related to portal hypertension from those with non-portal hypertension-related aetiologies in over 97% of instances.
- The ascitic white cell count is usually normal in patients with uncomplicated portal hypertension-related ascites and raised in those with non-portal hypertensive aetiologies, with the exception of hypoproteinaemic states and disorders associated with increased vascular permeability.
- A simple initial algorithm based on the patient’s medical history, physical examination and results of diagnostic paracentesis allows a focused approach to further investigation.