Hi all,

Our Fetal Screen package insert says that a positive maternal DAT can cause a falsely positive Fetal Screen. Does a positive Fetal DAT have any effect on the validity of the Fetal Screen? The package insert does not mention any.

Thanks in advance!

If by Fetal Screen you mean an antibody screen, then if the mother's antibody is IgG it can go through the placenta and circulate in the baby's own circulation and, depending upon the specificity, may actually sensitise the fetal red cells.

If, on the other hand, you mean Fetal Screen, as in the detection of fetal red cells in the mother's circulation, then I have never heard of the phenomenon.

Yeah I am referring to detection of fetal cells in maternal circulation. We had a limitation to proceed straight to a KB if either mom or baby was DAT positive. This limitation was being discussed and I think we will be getting rid of it altogether. We do not routinely run DAT's on Rh negative mom's so we wouldn't know if it was positive when performing the fetal screen, and in any case, a false positive fetal screen will reflex a KB just like a true positive will! 

I think was just hung up on the Baby DAT being positive, wondering if that would effect moms fetal screen but the package insert did not mention anything. I am thinking along the lines that if Baby DAT is positive it could cause a false negative fetal screen, if baby cells are already being bound by maternal antibody (but this would more likely be due to an abo incompatibility rather than Anti D and therefore not effect the fetal screen method?), but in that case those cells are also likely being destroyed already and so seems to me that the KB would also be falsely decreased.... thoughts? I may just be overthinking this...

Side note, I totally love the snowflakes and Christmas lights going on! Tis the season!

Thanks!

On 12/3/2021 at 9:15 PM, Danielle said:

Hi all,

Our Fetal Screen package insert says that a positive maternal DAT can cause a falsely positive Fetal Screen. Does a positive Fetal DAT have any effect on the validity of the Fetal Screen? The package insert does not mention any.

Thanks in advance!

I would consider this a non-issue as you would need to quantify any positives with a KB stain or flow cytometry anyway. 

On 12/4/2021 at 3:26 PM, Danielle said:

Side note, I totally love the snowflakes and Christmas lights going on! Tis the season!

Thanks!

Danielle,

I love the lights. When i'm feeling stressed, I come here and break em. If you haven't noticed, move over them with your mouse and they break with the most refreshing sound of glass breakage.

I hope you all don't think less of me now...