Why is Prenatest advised during 12th week of pregnancy?

Question

Hello doctor,

I am a 33-year-old woman. I am pregnant with my first baby in my 12 weeks. I had an appointment with my doctor two days ago, and she did an ultrasound to me, and she told me that th NT measure of the back neck of my fetus is 2.3 mm.

She asked me to do a blood test called prenatest to be sure of that. Please advice what should I do? I am attaching the ultrasound report (attachment removed to protect patient's identity).

Please help.

Thank you.

Answer 1

Hello,

Welcome to icliniq.com.

I understand your concern.

When NT (nuchal translucency) is towards higher value then a baby is more likely having a problem. Now there are two prenatal tests which can be done at 12 weeks. Most commonly done is a double marker test. Currently, both are screening test, and we come to know whether this pregnancy is high risk for some genetic disease like Down's, Turner, patau syndromes.

And if high risk than how much is the risk, statistically like 1:148, which means there is a chance of one pregnancy to come positive for downs in every 148 pregnancy. So for further confirmation have to send liquid around a baby for examination. In that, we remove fluid under sonography guidance and send it for examination.

They segregate fetal cells from it and do a DNA(Deoxyribo nucleic acid) test for confirmation. But this test is directly invasive and also have some possibilities of side effects, so we avoid on the first basis. Because if it comes as low risk in double marker than no need to send liquid around the baby. So consult with your gynecologist and have detail about which test is carried and possible results.

I hope this helps.

Kindly follow up if you have more concerns.

Thank you.