S.M.
if it were me I would not do the amnio, to much risk for introducing bacteria into a very secure environment!
we had a high risk of Down Syn. but we opted not to do the amnio just for the safety of the baby. knowing either way just wasn't worth the risk, and would not change the way we loved our child, I could easily prepare for either out come and for the most part the difference between healthy DS child and a healthy not DS child are the same for the first 6-12 months (with all due respect to DS children) both will spend the first 3 months eating sleeping and making a mess in their diapers just the same. We did go for further genetic testing/counseling (higher level Ultrasound) after our tri screen came out with a high risk (one in 4 come out that way regardless of there being a high risk or not). the Ultrasound at the Genetic Counselors office did provide better details into our son's little life, so hopefully that will give you more definitive answers to your situation. I cannot speak to your situation exactly but I did want to offer that the better Ultrasound will help a lot. Just please AVOID the amnio if at all possible, it is just not worth the risk, in my opinion (and that of my Dr.)
Best of Luck to you and your baby (and family)