personally, i think have amnio is a very personal decision. just to share with you, i had bad oscar scan results. 1: 30! and im only 26 years old! after much discussion and consideration with hubby, we decides to go ahead with amnio test just to make sure everything is ok. you may want to discuss the options available and the different situation may arises with your gynae.
dont worry.. i have heard of many unpleasant findings but it all turns out well for most mummies in the forum at the end of the day. they still have happy baby/babies! all the best! you will be kept in my prayers! =)