We currently have 2 obstetric patients who are typing serologically as A in the front group but are not reacting with anti-A or anti-B in the reverse group. Samples have been tested using Ortho, BioRad and tube techniques. We carried out ABO genotyping using the Innotrain RBC Ready Gene ABO kit. Both typed as AB.

 

We would currently recommend group O as the Red Book states that where the ABO group cannot be concluded group O should be given.

 

In both these cases it would seem that giving group A would be the logical choice but to do this we would have to decide whether the patient was a group A or group AB as we could not issue group A if there was no group in the IT system.

 

What I am wondering is what other centres do for such cases. 1) What ABO group should be entered into the IT system? 2) What ABO group should be recommended for transfusion?

 

I would not enter an ABO group into the computer system until the ABO type has been thoroughly investigated by a Reference Laboratory and, until that has been done, I would transfused group O blood.

 

Be VERY wary of ABO genotyping.  One only has to look at the ABO genotyping background in The Red Cell Antigen FactsBook to see how fraught with errors such a test can be.

Hi Malcolm

Thank you for your answer. We are a reference laboratory and have fully investigated the ABO anomaly  serologically using the techniques available to us. ie. Ortho and BioRad ABO reverse and newborn cards/cassettes. Tube ABO at 4°C and RT. In the past we would have done absorption/elution techniques to look for the presence of the B antigen and we may do this once we receive further samples but I am not sure how reliable this technique is . I am interested in what further tests you would perform to try and conclude the ABO.

Thanks for that catm.

 

To be perfectly honest, we wouldn't do any more than you have done (except that we would do adsorption and elution earlier in the techniques - that is not a criticism, that is just our way of doing things).  If we couldn't resolve the problem, we may send it to the IBGRL, but, as it is such a safe and easy option to give group O blood, I would not spend a huge amount of time, energy and reagents on resolving such cases down to the nth degree.

 

I'm getting too old!!!!!!!!!!!!!!

It might be worth checking to see if these two patients are related.  they may just have both inherited the same B variant........