Timing of blood draw for Fetal Bleed Screen test

[ksmith]

There has been some discussion at my facility as to the timing of blood draw for specimens to be used for the fetal bleed screen test following delivery. The issue arises during the middle of the night when we complete our cord blood testing & need to go draw a specimen from mom. Nursing & the patient doesn’t want to be disturbed in the middle of the night, which is understandable.

Of course, it’s better to collect the specimen as early as possible. Do you know of any references concerning the time frame of draw or have a facility policy you would be willing to share.

Thanks!

[David Saikin]

We usually draw with the p-partum HH; I've never seen sensitization (decades of experience) with drawing at this time frame.

[Mabel Adams]

Read your package insert for the fetal screen test. The Immucor one used to say at least an hour after delivery but asap after that. Many thousands of places did it with next morning draw as David said. It's been a lot of years since I have seen an anti-D in a female of childbearing age that they didn't know what stimulated it.

[Deny Morlino]

Our policy is the same as David's (PP H&H).

[Likewine99]

Our policy is the same as David and Deny. Keeping the patient in mind, does she really need to be awakened in the middle of the night for a blood draw when she is going to have an H&H in the morning?

I agree, check the package insert and see what it says. If you are still struggling w/this talk to your pathologist or the head of the L&D dept.

[GilTphoto]

Technical Manual says, preferably within 1 hour of delivery. Our phlebotomists draw the post partum specimen and pick up the cord blood at the same time.

The mother just gave birth, so you really don't have to worry about waking her, if it is drawn within 1 hour.

Some will be drawn for nothing if the baby is Rh negative, but we still report on the RhIG request: mom's ABO/Rh, baby's ABO/Rh, Fetal Screen=Not Indicated, RhIG Interpretation=RhIG is not indicated

Those who wait until morning will never find a FMH. Both the ante-partum RhIG and the ABO incompatible antibodies from the mother, will usually destroy most of the babies cells within a few hours if not collected early.

If your lab can say they haven't seen a positive Fetal Screen in over 10 years, that may be why!

We used to drawn next day, but we changed that.

[MAGNUM]

I am in agreement with David, we wait until the morning H&H to collect the fetalscreen, and YES I have seen positive FMH with the way we draw them, so GiLTphoto your statement is incorrect that we will NEVER find a FMH with the morning draw.

[Mary**]

We found one yesterday.

[MAGNUM]

I found one this morning also.

[GilTphoto]

I am in agreement with David, we wait until the morning H&H to collect the fetalscreen, and YES I have seen positive FMH with the way we draw them, so GiLTphoto your statement is incorrect that we will NEVER find a FMH with the morning draw.

OK, I'm sorry! Didn't mean never.

But there is the possibility of missing some, the longer the wait in collecting the post partum sample.

[Mabel Adams]

I found one a few years ago that actually required an extra dose of RhIG based on the KB and at that hospital they were always drawn with morning draw. We certainly had other pos Fetalscreens that did not turn out to be over 15 ml fetal rbcs on the KB.

There is certainly some basis to the ABO antibodies removing the ABO incompatible fetal cells so that they can't be detected. Before the days of RhIG they observed that moms that delivered ABO incompatible babies were less likely to become sensitized to D and what I read said they felt that these cells were destroyed intravascularly so were never presented to the immune system (spleen etc.) to cause sensitization. Thus if we can't find them in our fetalscreen test, they aren't there to sensitize either.

Fetal cells coated with anti-D (from antenatal RhIG) would be expected to circulate longer than ABO incompatible cells because Rh antibodies are notoriously poor complement fixers. If the cells weren't coated with enough antibody to make the spleen remove them, they should circulate more or less the usual life span of rbcs (although the Hgb F might alter that picture). I'm sure it all depends on the number of antibody molecules per cell, the number of D antigen sites left open, the mom's immune response, the size of the bleed and, for all I know, the color of the paint on the walls in Blood Bank, whether or not enough D pos cells would still be in circulation to make a Fetal Screen test positive. I just haven't really seen any unexplained anti-D's in the almost 30 years since the rosette test came out. Not that I have worked in huge places. It's great if you can get the sample drawn after an hour, but it does seem like it would take a policy like that above where they are drawn before the cord blood is tested.

[AMcCord]

Another place to check is the product insert for your RhoGAM (WinRho, etc.) The RhoGAM insert says to draw within one hour of delivery. We aim for that, but we are not inflexible.

[jbrun]

We also try to draw ASAP (within an hour) once we know a fetalscreen is needed (we generally obtain the cord blood type first). Our rationale is that the longer the time interval is from delivery to blood draw the higher the probability that fetal cells can be pulled out of circulation. We' rather obtain the specimen sooner and inconvenience the patient than have a false negative and put the patient at risk.

[Liz]

Once the cord blood confirms the need, you should then draw the mom, within one hour. Follow instructions (thats why there are SOPs based on inserts and Tech Manual). This is for the sake of quality patient-care and treatment and the sake of not-ending up in a medico legal case if you didnt follow instructions.

[hmust1]

I work in a <120-bed hospital and we draw FMHS specimens on demand, 60-90 minutes post-delivery. How many new moms are fast asleep an hour after they've delivered a baby? In my mind, risk always trumps inconvenience when you're talking about patient safety. Need documentation? Survey some moms and find out whether they would rather be inconvenienced by an overnight blood draw or face the risk of not being able to have any more children.

[Mabel Adams]

I should state that we have only waited to draw with morning labs for babies born late in the evening or at night. Others we tried to always draw asap after cord results turned out (which is probably not always very close to that hour, I'm afraid). At my current workplace we even try to draw those at night asap. Not all OBs get morning H&H's anymore anyway so waiting does not save them a stick. Didn't want to sound like I didn't care about the instructions.

[Liz]

Certainly not, Mabel, we know that I even had to go back to your post to see what you were referring to.

[ksmith]

Thanks to those who replied, you've been a great help!