We currently have a 50 year old male in house that had an accident that damaged his foot 3 weeks ago. He arrived septic and has had to have an amputation.
His ABO/Rh gives a B pos with a 4+ anti-D. His gel screen and panel give 1+ results that match up with an anti-D (all others rules out). His autocontrol was positive at 1+ by IgG, neg for compliment. The eluate results matched the original antibody ID. Presently this patient's specimen is on its way to our reference lab. Previous history at another facility lists him as B Pos, screen negative. As far as we know, he has never been transfused.
What are the possibilities (for what appears to be an D auto antibody), and how should he be treated?
By Jennifer G
Has anyone seen an Anti-D go from negative to 2+ positive to negative? We had negative antibody screens on an elderly A Negative woman from 2012 through 2018. 8 RBCs were transfused during this time. In August 2018, the antibody screen was 2+ positive, Anti-D was identified, and she received 1 RBC. In April 2019, the antibody screen was negative on 2 different occasions. The possibility of the August 2018 specimen being the wrong patient seems unlikely since we use hand-labeled separately armbanded specimens. However, I have never seen a true Anti-D behave this way.
Our facility is evaluating making a change to our process for Weak D testing for patients with a positive DAT. For years, if we were required to do a Weak D, but the patient had a positive DAT, we used to cancel the Weak D as invalid. Another hospital in our system mentioned that they tended to perform the Weak D, but then only cancel as invalid if the Weak D is positive. We are thinking about changing to this process, as we now have to result many babies as "Rh Unknown" and give their mothers Rhogam.
Per our Anti-D's package insert: "Red blood cells coated with alloantibodies or autoantibodies of the same or similar specificity as the reagent (i.e. cells that are DAT positive) may give weak reactions. This is due to decreased availability of antigen sites because of antigen blocking or steric hinderance. In extreme cases false-negative results may occur."
I'm worried about the "extreme cases" where a false negative could occur, but I cannot see this being common. Also, would you think that if the cells were coated with that much antibody, that we would see any other odd reactivity in the ABO/Rh? What do other facilities do?
Thank you in advance,
I was wondering if antibody titre is performed on a pregnant mother who previously had HDFN. According to the books, it mentions 'After the first affected pregnancy, the antibody titer is no longer useful'. Therefore does it mean that it doesn't matter what the antibody titre level is, and should be referred to fetal medicine specialist regardless? Or if there is more to this, I would be grateful for some enlightenment
I hope someone can help me with some clarification. I was reading about the presence of H antigens in different ABO blood group patients, but I am getting different answers depending on what I read. Transfusion Medicine and Hemostasis- Clinical and Laboratory Aspects- 2nd Edition mentions O > A2 > B > A2B > A1 > A1B with O having the most, whereas BBTS Introduction to Transfusion Practice-6th edition mentions O > A2 > A2B > B > A1 > A1B. Maybe it doesn't really have a big impact to my routine work, but it is still good to be in the know. Any thoughts would be welcome.