Transfusion of ? weak D patient

[Veronica Lee]

I recently worked with a 42 yr old female who was typed as Rh neg at one facility. When I typed her using Diamed Microtyping system, her D well showed a 2+ reaction. How should her blood type be reported and what units should be used for transfusion to this patient?

[John C. Staley]

First question, did the previous type at the other facility include weak D testing?

Second question, what is the current policy at your facility for a 2+ D test? At some facilities they would report it as negative, others would consider this patient as Rh positive.

[Veronica Lee]

I do not know whether weak D testing was done at the other facility.

At my facility the patient would be reported as Rh Positive. Can this patient produce anti D, and which is preferred for transfusion, Rh Pos or Rh Neg blood?

[stephanie sephel]

We no longer perform Weak D testing as part of their pretransfusin testing. We recently have seen several patients who are reacting variably with anti-D by immediate spin tube testing: negative and then weakly (1+) positive 2 months later. If anyone else is seeing this, what is your solution? Would you change their blood type from Rh neg to Rh pos or, based on the strength of the reaction, interpret as Rh negative?

[Ann Viernes]

The variation in strength of the D typing is indeed a sticky topic. It becomes more complicated when the D negative patient (not typed for weak D) has an autologous unit labeled D positive. We have been resolving each discrepency on a case by case basis. Some we are even treating as a suspected mislabeling. I'm almost tempted to return to typing all negs for weak D. Is the variation due to the antisera? Why is there so much variation in the monoclonal antisera even from the same manufacturer? Or do the individual's red cells express more D antigen at one time or another? I suspect there is not a simple resolution to the D dilemma, that would not unnecesarily deplete the Rh neg blood supply, result in unnecessary use of RhIg, excessive use of time and reagent (testing all for weak D), and repeated administrative decisions of what to call the blood type today. Then the problem remains, if your institution develops an internal policy, a patient undoubtedly will arrive from another facility that has a different policy.

[Eagle Eye]

I came across an autologous donor unit where Unit was labeled as O neg. Our primary method is Gel but we use tube technique for retyping of our donor units. WHen we typed our donor, donor type was undetermined or rhpos??. THis tech automativally ran rh control and control was positive. DOnor's red cell had positive DAT. First thing I suspected (QA brain??) mislabeling of the unit and called supplier. I was also curious that how come blood supplier typed unit as rh negative. Blood supplier used automation for donor typing.

[janet]

Our policy is: Patient considere Rh:positive if result is 2+ at immediate spin with one of our Anti-D's (we use 2 monoclonals, one will pick up VI but the other won't).

We did have a male patient form an Anti-D and Anti-C. We said he was Rh:positive based on the 2+ reaction, gave him Rh:positive units....low and behold at next admission there was the Anti-D

One never know what's going to happen!

[bernvil]

I recently worked with a 42 yr old female who was typed as Rh neg at one facility. When I typed her using Diamed Microtyping system, her D well showed a 2+ reaction. How should her blood type be reported and what units should be used for transfusion to this patient?

I would suggest that you try to establish the exact D status (deltions/DVI?) of the patient. Some of these patients may develop anti-D if transfused with D+ rbc - but most would not, and therefore it might be wasteful to use only D neg rbcs as a routine. (see AABB Tech Man 15. edit. p 323/4)

Stener Bernvil MD, Denmark