There were many questions on the last CAP survey that we received regarding Weak D. One asked "In the past year, how many Weak D positive patients with alloanti-D (immune/pregnancy induced) did you encounter in your facitily?" The vast majority answered "0", but there were over 170 that answered >5! I've not encountered 5 in my 33 year career! I'm thinking that these people did not understand the question, what do you think?

Those questions really weren't written well--at least not for how we do things. Plus, there is so much confusion about what we really mean by "weak D." Weak D types 1 & 2 may react at IS and not just by the weak D test depending on your anti-D reagent. Those category VI partial D's that react only with the AHG clone in some anti-D reagents are not called "Weak D type XXX", they are called partial D.

Although I have probably found about 4 D+ patients with anti-D in my 33 years, they weren't all "weak D" patients. In fact, I answered that question as "2" because we actually had 2 within one week back in January although one of them reacts weakly with anti-D at IS. She molecular types as a weak D type 2. If you don't routinely do AHG D typing you won't even know that the patient that made anti-D is truly a weak D.

I suppose there are a bunch of big reference labs that find a lot. In fact some patients may have been included in counts both by the reference lab and the hospital lab so were counted twice. Interesting point.

Obviously, we do not perform the CAP surveys in the UK, but I would wholeheartedly agree with Mabel (from what I have read) that the questions were thoroughly badly written. You just have to go to the website "RhesusBase" to see just how many Weak D's, Partial Category D's, Other Partial D's, incompletely characterised Weak and Partial D's and Del's there are now, and to lump these all under the umbrella of "Weak D" is crass.

CAP is not known for being "UP" the finer points of Immunohematology. Also recently they had an educational challenge where the patient was Rh+ with anti-D (which I can live with) - however the auto control was positive/DAT negative. When I conacted the MD who did the discussion, she never responded - how typical.

This is revealing, though, in one sense. There is quite a bit of variation in how labs handle weak D testing: whether its done at all, only for prenatals, reported as positive if 2+ and above only, etc. There is another thread here about weak D testing that showcases this variation.

We currently have a student doing a research project on the issue. Out of four hospitals in our area, we have found that there are four different protocols regarding how weak D testing is done! So the fact that this one question causes so much confusion is not too surprising. Who knows, those sneaky devils at CAP may have worded it ambiguously on purpose just to see what kind of backlash they get!

Scott

I'm glad I'm not the only one who thought those questions were poorly worded.

There were many questions on the last CAP survey that we received regarding Weak D. One asked "In the past year, how many Weak D positive patients with alloanti-D (immune/pregnancy induced) did you encounter in your facitily?" The vast majority answered "0", but there were over 170 that answered >5! I've not encountered 5 in my 33 year career! I'm thinking that these people did not understand the question, what do you think?

Thanks for starting this discussion. I also was a bit bewildered on how to respond.

I had the exact same thought, >5 in a year?!? Holy haberdashery, Batman!

It's hard to answer clearly when you don't know what they mean by "weak D" in a given question.

I agree with David, CAP is not always up on what we currently do in practice in our labs. I currently do lab IS and build our Blood Bank system for multiple sites. This weak D thing wears me out!!!

This weak D thing wears me out!!!

Me too!

I just love explaining to the physicians why we've decided to 'change' their patients blood type.