Combined screening test - insufficient fetal dna

[WelshMammy123]

Hi,

Wondering whether anyone has experienced anything similar?

I had my 12 week scan and combined test done over 2 weeks ago. NT was 1.2mm. I had my bloods done and was told if they came back high risk I'd hear within 3 days.

I hadn't heard anything so assumed all was probably ok. Got a call today from the hospital today to say that there was not enough fetal dna in my blood sample and so they have not been able to do the test.

The hospital want me to go in to do another blood test. I asked whether I should be concerned and was told that this sometimes just happens but wondered if anyone had had a similar experience?

I'm on clexane and baby aspirin and am wondering if that might have affected the result as my blood will have been thinned.

Would welcome any thoughts/experiences on this. I lost my last baby due to a chromosomal abnormality (not genetic) so I'm extremely anxious this time around.

Thanks.

The blood test must have been for NIPT rather than the standard NHS combined screening as they don't look at the fetal DNA for that. I don't think it's anything to worry about, it happens reasonably often.

Thanks for replying. My midwife said to me that they were offering NIPT but I thought she said that this was only done if the combined screening test showed you as high risk. Surely they'd tell me that ahead of doing the NIPT. Wondering if my hospital (Whipps in London) is part of a trial where they have moved to NIPT as standard?

I didn't think to question it when they called.

Definitely a NIPT as that’s what tests the fetal DNA. I wonder if you were put through for one automatically due to your previous loss?
The way I understand it (and have been in your shoes with a chromosomal issue on a previous pregnancy so I totally understand the anxiety) they need at least 4% fetal DNA to do the sample. It can be affected by all sorts of things - mothers BMI being one I know of as I was worried about that myself.
It’s not unusual for it to happen depending on the test - some have higher rates of redraw than others.
Have they arranged a time to come back and get another sample? It should only take a week or so to get the results - good luck I am sure you’ll be fine.