We had a fabulous 12 week scan today, but a very confusing high risk for Downs Syndrome result.
Bub looked great and was dancing around, showing us he'r high kicks and juggling skills. Brain and heart development looked great; measuring on target for dates; hands and fingers, feet and toes in all the right places. We were told the nuchal fold measurement was within the normal range. Everything looked great!
The Doctor came in and we discussed our PGD results. She said she wasn't sure how that would effect the Downs risk result as the statistical approach doesn't allow for that to be taken into consideration. When she finally got back to me in the afternoon, I think she was as surprised as I was with the combined results of 1 in 38 chance of Downs.
Due to the combined risk of my age and IVF, my baseline risk was 1:70. Apparently the nuchal fold measurement was actually on the higher side of normal and the maternal serum blood test showed my hCG again normal but on the high side of the range, while the pregnancy protein marker (PAPP-A?) was on the lower side of normal. All these together doubled the risk.
My confusion comes from this: how can these figures be accurate if they do not take into account the following VITAL information?
1.) This embryo has already been tested for Downs (and several other chromosomal abnormalities) and was given a tick of approval considered to be >90% accurate
2.) The baby's nasal bone could be clearly seen on ultrasound (this is often absent in Downs babies)
3.) The long bones appeared normal on ultrasound (Downs babies often present with shortened femur and humerus bones)
We now have to decide whether or not to do a CVS or amnio. We are somewhat stuck on the point that we believe we have already tested the chromosomal makeup of this baby. We've taken so long to get to this point - why should we risk miscarriage to re-test something we have already tested? Are the tests in fact the same, or am I wrong? If we do opt for further testing should we go CVS and find out now, or wait another 3-4 weeks for an amnio?
I feel I'm in deep water here. Any advice and/or sharing of experiences would be greatly appreciated.