Portal vein velocity decreases with advancing cirrhosis.

Normal maximum portal vein velocity (MPVV) ranges from 20 to 30 cm/s, but it is significantly reduced in cirrhotic patients, averaging 13.9 cm/s.

This velocity progressively drops as the disease severity (Child-Pugh score) worsens, and in severe cases of cirrhosis (Child's C), the flow can even reverse completely (hepatofugal flow).

A portal vein flow velocity of less than 15 cm/s is a strong, independent predictor of future portal vein thrombosis (PVT).