Pictorial review: Colour Doppler ultrasound flow patterns in the portal venous system.

Doppler ultrasound is a well established method for assessment of the portal venous system to detect the direction of portal blood flow. It is helpful for non-invasive diagnosis of intra-abdominal portosystemic shunts, especially in patients with cirrhosis. Less attention has been paid to other influences on portal venous flow, e.g. tricuspid regurgitation, increased hepatic out-flow resistance, respiratory cycle. The aim of this pictorial review is to describe the spectrum of physiological and pathological Doppler ultrasound flow patterns in the portal venous system.