How do you handle reporting the Rh on a cord blood with a positive DAT... and an apparent false positive Weak D test?

We have been calling the Rh indeterminant and recommending RhoGam for the mom.

Any body doing something else or further workup?

Thanks,

LF

We had this exact situation a few weeks ago. We called the baby Rh indeterminant and recommended that the mom get Rhogam. It was a bit confusing to the floor because the tech had reported the baby as Rh negative before doing the DAT and the weak D but after I explained why we needed to do this they were fine with it all.

We treat the cells with EGA to remove the antibody, then proceed with the weak D test. We haven't had to do one for a long time.

I think Mabel Adams is doing great serology. whenever possible, determine the Correct Rh type of these babies so there is no confusion. Just be sure you follow the package insert for the test and/or validate the test if outside the package insert's recommendation for use. EGA is used to strip IgG from the RBCs to facilitate typing by the IAT when the RBCs have a negative DAT.

Marilyn Moulds, Immunohematologist, Lecturer and Educator

I think Mabel Adams is doing great serology. whenever possible, determine the Correct Rh type of these babies so there is no confusion. Just be sure you follow the package insert for the test and/or validate the test if outside the package insert's recommendation for use. EGA is used to strip IgG from the RBCs to facilitate typing by the IAT when the RBCs have a negative DAT.

Marilyn Moulds, Immunohematologist, Lecturer and Educator

This works fine if your laboratory has access to reagents such as EGA. In the event that you do not then you have to err on the side of caution and give the mother RHIG.

EGA is available commercially as a kit, which has a good experiation date and can be used in other situations for removing IgG for typing RBCs for other antigens, or there are procedures for making up the solutions and validating them. I understand that small laboratories may not be able to keep the kit or solutions, but most reference labs have them. Marilyn M

Thanks. I have used EGA in this exact situation at another facility that functioned as a reference lab. It is good information. I was just pointing out that not all facilities use this reagent and often reference labs take longer than the time allowed for the facility to make the decision of whether or not the mother actually needs RHIG. Our hospital often discharges after 24 hours which would not make this a timely option for us and I'm sure other hospitals operate in a similar manner.

We use gentle heat elution for cord bloods to elute IgG antibody. We set our waterbath to 45 C and gently agitate a 4-5% suspension of cord blood (may take up to 15 minutes). The weak D test can the be performed and on most specimens this is successful. We also stock EGA for the stubborn ones. This may be a simple, cheap solution for smaller labs. We don't read the weak D test microscopically (follow reagent manufacturer's directions).

Dear Beverly: you are soo good. Helping blood bankers do simple tests that do not need commercial reagents and/or complicated procedures to make their own reagents. Who says the "old" reliable procedures will not still work today! With blood bankers like you I think I need not worry about the future of blood banking without us "oldies". Marilyn

The most important thing is patient safety. However, we approach the goal is dictated by who we work for. So there will be many methods of achieving the same goal.