Should I trust the NHS combined tests?

[PuddingPie16]

Hi Everyone,

We received some sad news yesterday at our 12 week scan that one of our twins has an abnormality - Anencephaly to be precise.
Twins are DCDA so have separate sacs and placentas.

The midwife/sonographer was quite anti-testing the healthy looking twin because she said the results from the poorly twin may affect the outcome? I'm also led to believe that result accuracy for DCDA twins is less accurate anyway because it doesn't necessarily pick up for both? (Not sure about this)

I'm due to see a Consultant next week to discuss options of continuing with the pregnancy but I had a call from the midwife yesterday saying the lab had agreed to do my combined screening tests with the blood and 1.3 NT that had been taken, taking into account I'm 31 and have no health conditions.

Does anyone else find this strange? The midwife/sonographer (same person who called me) wasn't keen on me doing the test and I was okay either way with what their advice was. Then she calls me and tells me they are going to run them.

I'm just a bit concerned that the result accuracy is difficult anyway but adding in an already known abnormality, may affect potentially an otherwise healthy outcome of the other twin? I just have a horrible feeling I will be getting a call about high odds and go through that alongside discussing losing the twin too..

I'm sorry you haven't had good news.

I'm surprised you were told the test isn't accurate? I had DCDA twins earlier this year - I was given a "score" for each twin on the combined test and also paid extra for the NIPT panorama (blood test sent to America) as you get an individual score for each twin with that test also?

I did the NIPT after some bad genetic testing results on a previous IVF collection so read Up about what happens if there is an issue with one twin and read that selective reduction when you have DCDA is low risk to the healthy twin - definitely in the first trimester and up to around 16 weeks or more

So the results for the unwell twin will only affect the results if the unwell twin has a chromosomal issue. The screening combines your NT measurement, your demographics and the blood test which looks for certain factors that could potentially indicate a chromosomal abnormality (Beta HCG & PAPP-A). Obviously it’s hard to know if the twin with anencephaly has a chromosomal issue which has caused the anencephaly but if it’s just a very sad anomaly finding that happened during development then it shouldn’t affect the screening. I’m not sure if that makes sense, I hope it does! Sorry you’re having such a rubbish time, this must be really hard for you x