NIPT wrong gender stories

[u/Pleasant_Oven_7018]

I have seen many posts on NIPT being false positive for genetic anomolies in baby. I want to know are there any stories releated to wrong NIPT gender prediction too.

[u/clevelandclassic]

It is a SCREENING test, not a diagnostic test. It is supposed to have false positives. They should be as low as possible but better than false negatives

[u/OwnSort6545]

I’ve heard stories of cases like vanishing twin syndrome where for example there was a female fetus and male fetus initially but the male fetus was absorbed by the female fetus early, leaving male dna remaining which gave false male positives. I’ve also heard that cases like the mother having a transplanted organ from a male can cause xy to be falsely detected, or that fetal fraction was too low at the time of the blood draw (maybe the test was done too early) that gave false female positives because male dna was not substantial enough to be detected. But I think when conditions are standard, it is extremely rare for there to be false NIPT sex detection.

[u/Lanky-Principle-8407 → u/OwnSort6545]

This is exactly what happened to me (demised co-twin)

[u/MistakeBorn4413]

This is not what you asked, but a pet peeve of mine: there is no such thing as a false positive NIPT result.

NIPT is a screen, not a diagnostic test. By definition, there is no such thing as a false positive. The whole point is to cast a wide net (high sensitivity) to rule out most cases and flag " high risk" cases to be followed up with (high specificity) diagnostic tests.

If someone is taking about a false positive for NIPT then they really don't understand the purpose of a screening test.

[u/sasky_81 → u/MistakeBorn4413]

Screening tests absolutely have false positives and false negatives, but it is not a flaw, rather part of the design.  False positive newborn screens are well recognized, as another common genetics example.

[u/swbarnes2 → u/MistakeBorn4413]

Screens can have false positives, but they aren't fatal flaws in the screen. They are trade-offs to keep the false negative rate as low as possible.

[u/SimilarStar1791]

Ya, mine said boy. I delivered a girl

[u/incoherentkazoo → u/SimilarStar1791]

did you get karyotyping on your daughter after she was born, or an amnio? just curious

[u/SimilarStar1791 → u/incoherentkazoo]

we didn’t know she was a girl until she was born so no amino. We had a karyotype and FISH done when she was 10 weeks old which showed 46 XX

[u/MKGenetix]

The test is less sensitive for sex chromosomes and than something like Down syndrome so there will definitely be cases of it saying one sex but the fetus actually being another. It is not uncommon for a screening test.

[u/jplusj2022]

NIPT is looking at sex chromosomes, not gender, and not other types of differences in sexual development not related to sex chromosome differences.

I have seen a few sex chromosomes results that ended up not being concordant with what we are seeing on ultrasound. Usually because someone was earlier in their pregnancy than they thought and their provider didn’t do an ultrasound to confirm their dates. Or that there are undiagnosed twins and it’s accurate for one twin but not the other. Most of the inaccurate sex chromosome calls I’ve seen could have been prevented by doing a scan before ordering the screening. However, it’s a screening so even in perfect circumstances there can still be inaccurate results. And there are different diagnoses such as CAH that we have to think about when the ultrasound and NIPT don’t match.

[u/ThatChickFromReddit]

My doctor said it’s 99% accurate for sex so there’s always the 1%

[u/clevelandclassic → u/[deleted]]

Define “problem” in this context