What are the chances NIPT shows positive for Down syndrome?

Question

Hi doctor,

I am a 30-year-old female, and my NT scan has come normal, but the dual marker test is positive for Down syndrome. Therefore, I have given blood for NIPT.

What are the chances of the NIPT result to come positive for Down syndrome?

I would greatly appreciate any guidance.

Answer 1

Hi,

Welcome to icliniq.com.

I read your query and understand your concern.

Double marker test shows an increased risk of Down syndrome (1:46). The NT (nuchal translucency) scan detects 70 percent of prenatal Down syndrome cases. The double marker test detects 60 percent of prenatal Down syndrome cases.

So the two tests combined the NT scan, and the double marker test detects 90 percent of prenatal Down syndrome cases. Also, the double marker test has a role in showing how is the placenta working.

As there is increased risk in your case, the next best test is to do a NIPT (noninvasive prenatal testing) which is a more sensitive test for Down syndrome. NIPT is quite accurate for Down syndrome 99 % and 18 (97 %) for trisomy.
It needs to be more accurate for trisomy 13 (87%). The results of NIPT take around two to three weeks to come. So you have to wait two to three weeks for the results.

Hope this answers your questions. Feel free to reach out for any further questions.

Kind regards.