First of all -the results ARE iffy, so you're right there, but I'm always a little miffed at the women on here who act like the ONLY reason any of us get prenatal testing is so we'll know if we want an abortion. That's not true- what IS true is that if you are going to have a special needs child, you need to be prepared and often, the medical team needs to be prepared. There are some defects that could mean the difference in life, death, sickness or severity of the defect depending on how fast your newborn is treated after birth. I think it's smart to have prenatal testing and screening -if for no other reason that being prepared (both you and your doctor).
There are, sadly, some terrible genetic defects out there that mean that your baby will die in your 3rd trimester or very soon after birth. I know two people who had pregnancies where this was the case. Had you rather know now, when it's still going to hurt like hell and be traumatic, but at least there's not a nursery, shower gifts, etc. in place -or wait until it happens and then have to deal with all of the baby stuff you're surrounded with. I know that sounds horrible, and hopefully your baby is 100% perfect, but the Boy Scouts are onto something with their motto: "Be Prepared"!
Despite what some misinformed people on this board will tell you, the CVS (and you're too far along now) or an amnio are the only way you can be 100% sure of any defects or no defects related to genetic issues and others they can test for. They can tell a lot with ultrasound, but at least the pre-tests let you know if there's a HUGE reason to have an amnio or not much reason at all. The reason the statistics on amnios do not read 100% accurate, is once in a while, not enough fluid is collected for accurate testing. This makes up the .2 -.4 % In 2010, there is also only a .1% chance of miscarriage -and even that is iffy because many of the women who miscarry after an amnio would have anyway, but because they had an amnio, it goes into the statistics.