Had an abdom. US with Doppler. What does "The main portal vein is antegrade" mean? The Doppler in an abd. US only shows the portal vein flow, nothing else?

Above means no P Ht. Doppler US .—The direction of blood flow may be described in two fundamentally distinct ways. The first is to describe flow with respect to the circulatory system.The term antegrade refers to flow in the forward direction with respect to its expected direction in the circulatory system. The term retrograde refers to flow in reverse direction , seen in severe portal hypertension.
Antegrade . portal vein flow is normal. It means the blood in the portal vein is flowing towards the liver. Doppler can evaluate any blood vessel that can be visualized. I can't tell you why they specifically mentioned the portal vein in your report, it may be part of their protocol, or maybe there was a clinical question of portal hypertension or some other pathology involving the portal vein.