Rhogam for Weak D pos OBs

[SandyR]

If the trend is away from Weak D testing on OBs so they are reported as Rh negative based on an immediate spin reaction, how are other facilities handling the fetal bleed screen after delivery? Thanks for any ideas.

[Diane]

I'm not sure I understand what you are asking, but we use Ortho's "Fetalscreen" kit to detect the presence of fetal cells in Mom. If you were thinking about using weak D testing to detect fetal bleed, the weak D test is no longer considered acceptable for that purpose. Hope this helps.

[David Saikin]

The fetal bleed screen will usually be macroscopically positive on these weak D pts. There is no alternative but to screen for fetal hgb in order to detect fetal-maternal hemmorhage. You could do a weak D test . . . if positive do you give RhIg?

[John C. Staley]

You have a positive fetal screen, you do a weak D test and it is positive. Are both positive because mom is weak D positive or has there been a significant fetal bleed or, heaven forbid, both? This is the question you need to ask your self. I would think the the only reliable way to determine the difference would be a test for fetal Hgb, either flow cytometry or the oft maligned K-B stain.

[BSIPHERD]

Except for neonates and prospective fathers, we report patients who type as Neg to 1+ with Anti-D on Immediate Spin as Rh Negative. (Exception: Patients known to be Rh Pos who receive many units of Rh Neg blood.)

If an OB patient has previously been typed as weak D positive, we skip the Fetal Screen and go right to a K-B to determine fetal bleed.

If we haven't previously typed the patient for weak D and the fetal screen is as strong as the positive control, we do both a K-B and a weak D test. If the patient is weak D positive, then for any subsequent pregnancy, we'd go right to K-B as skip the Fetal Screen if we needed to test for fetal bleed (i.e. delivery of Rh Pos baby).

[SandyR]

Thanks for the input. Since we're no longer doing weak D testing on moms we were looking at reflexing any positive fetal screen to a weak D test before moving on to a K-B. Are there many folks out there using flow cytometry? And if so what kind of instrumentation?

Thanks again.

[Tekk56]

Really, unless you have a history of a weak D on a patient, or have =/- reactions, there would be no "clue" for you to go straight to fetal cell quantitation and if you have a positive fetal screen you would perform quantitation anyway, right? So who cares about the weak D status?

[Tekk56]

Really, unless you have a history of a weak D on a patient, or have =/- reactions, there would be no "clue" for you to go straight to fetal cell quantitation and if you have a positive fetal screen you would perform quantitation anyway, right? So who cares about the weak D status?

... to above: " +/- "

[labgirl153]

Regarding the next step when a positive fetalscreen is seen (since it's uncommon that it's positive):

Part of it is curiosity: "why isn't the K-B positive in light of a positive fetalscreen?" Sure, it could be that the bleed is too small to register in the K-B, (first line of reasoning), but the weak D testing on mom is a quick, painless way to get a direct answer.

Two, as the others noted, if she is weak D pos, then for future reference, it makes sense to note it for the next tech: skip the fetalscreen and jump right to the K-B.