High risk problems

My ultrasound tech keeps telling me that my baby's kidneys are a little large and that's a sign of Down syndrome.. I've asked around about this and nobody seems to know what I'm talking about or how the kidneys and Down syndrome are linked. Not even my doctor! I also have a close friend who has a son with Down syndrome and even she says that sounds ridiculous. Anybody else went through this? Spare some advice because I'm really worried