Gestational age for fetal screen

[David Saikin]

On Wednesday, May 25, 2016 at 1:27 PM, BankerGirl said:

hWe just had a mom with an incompetent cervix who had been bleeding for several days (4 days that we know of) deliver a stillborn at 22 weeks gestation.  Our second shift tech performed a KB and the result was 0.9% with recommendation of 3 vials RhIg.  I wasn't here to look at the slides but a second tech verified with the performing tech.  We didn't get any cord blood so don't know the fetus' Rh status, but from what I'm reading, that seems an unlikely percentage for 22 weeks.  We did give the poor lady all three vials, but it seems like a lot.

I once had to give 7 vials for a large positive KB - it was a C section and the doc said he really had to manipulate the placenta to get it out.  They bolused the shots into 2 syringes.

[BankerGirl]

David,

I too have given moms of full term newborns many more vials but my concern is that the fetus was only 22 weeks.  It would seem that is a lot of blood to come from such a small one.  That is my only question.

[Malcolm Needs ☆]

49 minutes ago, BankerGirl said:

David,

I too have given moms of full term newborns many more vials but my concern is that the fetus was only 22 weeks.  It would seem that is a lot of blood to come from such a small one.  That is my only question.

Remember that the leak from baby to mum may be chronic, but at a very low level per day, so that the baby will compensate (to a certain extent) for the loss by making more red cells, but that the red cells that leak into the mother's circulation will last as long as normal ede cells would last (as long as they are ABO compatible, and the mum hasn't got any other antibodies that may destroy the fetal red cells), which can all explain why the bleed from the baby sometimes looks incompatible with life, but the baby seems (relatively) well.

[BankerGirl]

Well, in this case the mom came into the ED several weeks previous with suspected threatened abortion and received RhIg so I was surprised that any fetal cells would survive in mom's circulation.  I guess anything is possible, especially since the infant was stillborn.  Time to move on.

[Malcolm Needs ☆]

Oh sorry; I didn't realise the baby was stillborn.

Even then though, if the bleed was chronic, but of a larger volume than I thought at first (and as long as the baby/foetus was alive when the lady came into the ED, which I would imagine was the case, otherwise they would have kept her in then), the anti-D immunoglobulin can be consumed  by the foetal red cells in the Mum's circulation quite quickly, and then more foetal red cells from the chronic bleed would then survive normally, and, until the IUD, the baby's/foetus's erythropoiesis would continue to function.