Ultrasound demonstration of changes in the normal portal venous system following a meal.

Eating might be expected to change vessel size within the portal venous system. The diameters of the portal and superior mesenteric veins were measured in thirteen normal individuals using B-mode ultrasound, initially fasting and then following a meal. We have shown a 50% increase in the diameter of both these vessels occurring between thirty minutes and one hour after a meal. The significance of this is discussed.