Final answer:
Portal hypertension in cirrhosis leads to ascites in the initial phases due to increased hydrostatic pressure within the hepatic sinusoids.
Step-by-step explanation:
In the initial phases, portal hypertension leads to ascites due to increased hydrostatic pressure within the hepatic sinusoids. Portal hypertension occurs in cirrhosis, where scarring of the liver obstructs the flow of blood through the liver. This causes portal systemic anastomoses to develop, allowing blood to bypass the liver and return to the heart without undergoing detoxification. The increased hydrostatic pressure within the hepatic sinusoids causes fluid to leak into the abdominal cavity, leading to ascites.