My 13 year old son went to the doctors today due to one of his testicles being high up in the sac. what does this mean? hes been referred for a scan

It happens: The testis travel with their blood supply from their origin next to the kidneys down into the sac, usually by 28-34 wks in pregnancy. Some don't make it all the way. The work better if they at positioned properly. Sometimes a muscle holds them high in the sac. I wouldn't stress at this point. The scan will document normal blood flow/size/function.