What is the most common cause of ascites in patients?

Portal hypertension is the most common cause of ascites in patients, primarily due to its role in liver disease and cirrhosis. This condition leads to increased pressure in the portal venous system, which can cause fluid to leak into the abdominal cavity. The excess fluid accumulation results in ascites, characterized by abdominal distension.

The pathophysiology involves various factors, including an imbalance between hydrostatic and oncotic pressures, as well as alterations in renal function due to impaired liver function. Patients with cirrhosis, especially, are often seen with ascitic fluid due to the hepatic portal system's dysfunction.

While nephrotic syndrome can cause ascites due to lower oncotic pressure; bacterial peritonitis can lead to ascites as a complication but is not a primary cause; and uterine malignancy can cause fluid accumulation via carcinomatosis or obstruction, they are less common reasons compared to portal hypertension in the general population. Therefore, understanding the prevalence and mechanisms involved in portal hypertension is crucial for recognizing ascites in clinical practice.