[Duplex sonography of the normal portal vein].

In 50 normal subjects flow velocity and direction on the portal vein was measured by ultrasonic duplex system. The measurements revealed at a mean diameter of 9.7 mm, a mean flow velocity of 15.2 +/- 2.6 cm/s, corresponding to a volume flow of 693 +/- 235 ml/min. Postprandially this increased to 880 +/- 269 ml/min. Inter-observer and day to day measurements demonstrated good reproducibility. Thus, this simple non-invasive method is well suited for quantitative assessment of the portal vein system in portal hypertension, thrombosis or after shunt operations.