[Kliehauer-Betke or Fetal Bleed screen when infant is weak D (by testing)]

Yes; a weak D infant could cause an Rh-Neg mother to produce of an allo- D in the mother with a significant fetal/ maternal hemorage. And, Yes, a KHB should be performed in order to determine the number of RhoGam vials to be administered. Ultimately, we strive to circumvent the production of an allo-D in the mother such that future pregnacnies will not be jepardized. We utilize the FMH screen as a qualitative precursor to performing the KHB, which is quantitative. In other words, if the FMH screen is negative then no KHB is needed and one vial of RhoGam is administered; if the FMH screen is positive then we proceed with the KHB and calculate the number of vials of RhoGam to be administered. An Rh-Neg mother's immune system can recognize a weak D, do to decreased expression or protein alteration, as being foreighn and therefore produce an allo-D. You must remember that the FMH detects fetal cells via presence of D Ag where the KHB detects fetal cells through staining fetal Hgb.

Hope this helps. :)

Are you saying you do not do the K-B if the FMH screen is negative? According to the screen package insert it says that with a weak D infant the screen may not be positive even with a greater that 30ml. bleed. We are currently not following a negative screen with a K-B, although I am not sure how many if any infants we have had in these cases that are weak D since we report these babies out as RhD positive.

[Kliehauer-Betke or Fetal Bleed screen when infant is weak D (by testing)]

Is anyone calculating FMH by Kleihauer-Betke when the mother is RhD neg and infant is weak D? Since with regular testing we cannot determine if infant is weak or partial D we treat all those tested as weak D as if they could cause immunization. However in package insert for Fetalscreen test (using rosette method) it says that the screen may be falsely negative if the infant is weak D. Should we then require that a Kleihauer test be done in these cases? Of course we all hate the K-B in our chronically understaffed BB. Could the weak D infant cause the mother to need more than one vial of Rhogam even with a bleed of more than 30 mL?