A sample was sent to us on a 32 year old pregnant patient about to deliver. Historically she was an A Positive but she presented this time as an O Positive. The reverse typing was 2+ with A1 cells and 3+ with B cells. We have seen cases where the ABO antigens were decreased or altered during pregnancy but this was the first case that I have seen in 35 years where the A antigen was not detected. We performed an adsorption/elution study and the patient did adsorb and elute anti-A. I thought this was interesting and wanted to share; without a history this lady could have been called an O Pos. She typed as A1-, but we doubt the typing since there wasn't any reaction with monoclonal anti-A.

After a night on-call and a day working, I am really tired and going to bed, BUT, this sounds reallyinteresting att. I'll sleep on it and have a think - but I may well have more questions than answers!

Thank you for posting this case.