Caveat Question

[SMILLER]

We came across a report from a reference lab (not a BB specialty lab, and not one we routinely use ourselves), that had this comment after the results for a negative prenatal type and screen:

"This test is intended as a screen to detect those IgG antibodies implicated in hemolytic diseases of the newborn. It does not routinely detect IgM antibodies and thus is not suitable for screening for irregular antibodies prior to transfusion."

We are debating why this lab thinks that this disclaimer is necessary. I have an idea, but I wonder if anyone else has any thoughts.

Thanks, Scott

[Malcolm Needs ☆]

Seems rather like the same get out clause we use, for legal reasons.

We never say that there were no atypical alloantibodies (or no additional atypical alloantibodies) present.

We always say that there were no atypical alloantibodies (or no additional atypical alloantibodies) detected, and then go on to state which techniques we used.

In this way, if there is an antibody directed against a low frequency antigen present (such as anti-Vw) that we have missed because it was not expressed on the red cells we used for testing, we won't go to jail!

[John C. Staley]

I do believe that is what we have for years, fondly referred to as the : CYA statement!

[SMILLER]

Seems rather like the same get out clause we use, for legal reasons.

We never say that there were no atypical alloantibodies (or no additional atypical alloantibodies) present.

We always say that there were no atypical alloantibodies (or no additional atypical alloantibodies) detected, and then go on to state which techniques we used.

In this way, if there is an antibody directed against a low frequency antigen present (such as anti-Vw) that we have missed because it was not expressed on the red cells we used for testing, we won't go to jail!

Thanks, Malcolm. Can you tell me the special significance of the IgM part of the comment?

If I am not mistaken, detecting IgM can help in predicting when an otherwise IgG titer starts to rise, but I am not sure why they mention it in regards to a transfusion when reporting out pre-natal screening results. I wonder if they have their disclaimers mixed up a bit.

Thanks, Scott

[Malcolm Needs ☆]

I do believe that is what we have for years, fondly referred to as the : CYA statement!

Spot on John!!!!!!!!!!!!!

[Malcolm Needs ☆]

Thanks, Malcolm. Can you tell me the special significance of the IgM part of the comment?

If I am not mistaken, detecting IgM can help in predicting when an otherwise IgG titer starts to rise, but I am not sure why they mention it in regards to a transfusion when reporting out pre-natal screening results. I wonder if they have their disclaimers mixed up a bit.

Thanks, Scott

Well, almost all antibodies, including anti-D, can be IgM only when they are first formed, but things like anti-Jka or anti-Vel and some others can "stay" as IgM, but may not cause agg;utination without some form of potentiator - but I do agree that they could have made their statement more succinct (that, coming from me?????????!!!!!!!!!!).

[Mabel Adams]

Yeah, it's the IgM part that seems strange. If they are testing with anti-IgG rather than polyspecific then so are the rest of us, including for transfusion. I think it is a CYA statement written from the reagent package inserts by someone that doesn't entirely understand the testing. Or maybe it was written a very long time ago when polyspecifica AHG was more the norm.

[kate murphy]

Or perhaps the technique they are using has no intermediate steps that would show an IgM antibody. Capture sandwich technique will not show an IgM antibody. Or maybe they're using PeG and only have an anti-IgG reading.