First Trimester Screening ?s

Hello Doctor, I am 33 years old and 14 weeks pregnant for the first time following IVF.  I had my first trimester screening last week ( at 13 weeks) which included the NT measurement with the PAPPA and beta-HCG blood tests.  I received a call from the genetic counselor on Friday saying that my risk for Down's Syndrome is 1:110.  Fortunately, I was able to get the newer blood test, versus CVS or amnio, that looks at chromosomes in my blood from the baby and can determine whether or not the baby has trisomy 21.  I will have to wait two weeks for the test results and I am extremely anxious and haven't slept well or been able to concentrate since I heard the result.  The NT measurement was 2.2 and the PAPPA I believe was .70 or .75 and the beta-HCG I believe was 1.8. I don't have the results in front of me, but I am fairly confident those were the numbers they showed me Friday. The counselor said the numbers were in the normal range, but that the decreased PAPPA compared to the HCG increased the risk.  I guess my question is after reading about the screening test and the 5% false positive rate, is my risk truly 1:110 or is it only 5% chance that the fetus is unaffected?  I also believe the sonographer noted the nasal bone to us during the scan,  but now I am not sure. Would that be a positive sign? Any help clarifying would be very helpful.
Thank you!

[Elaine Brown, MD]

Hi!
I am not 100% sure that I understand your question, but I DO want to clarify that the test results/scenario you have provided certainly do NOT suggest that there is only a 5% chance that your fetus is unaffected.
In other words, that would translate to a 95% chance that the baby IS affected, and your risk is much smaller than that.
How I would frame your results to a patient of my own is to say that 1 woman out of 110 women with the same results would be expected to be carrying a fetus with Down's syndrome and the other 109 would not.
I hope that helps you to look at your odds in a different light.
How very cool that you could get the new blood test and avoid CVS/amnio!
Good luck!
Dr B

[lloyd1987]

sorry for posting here but it wouldnt let me post my own thread..

[lloyd1987]

i had my last period which started sept7th and ended sept 11th....i took a test about2 and a half weeks later was negative..then almost two weks after that took another urine pregnancy test at dr. and was positive...was wondering when i conceived...do you think its possible i conceived a few days before my last period sept 7th or after sept 11th my last period?

[lloyd1987]

someone plz help

[lisas9]

It is most likely that you conceived after your last period. Your first ultrasound will give you more accurate dates. If it is a question of paternity then a dna test would be needed to confirm if the dates are less than a month apart.

[lloyd1987]

from today from what ultrasound read im 6 weeks 2 days....so when did i possibly conceive?