This past March we had a patient come thru the Emergency Department who was pregnant and spotting. A Type and Rh were performed at that time with a result of O Negative using the conventional tube system. She is now back in the facility delivering but testing as O Positive in the Gel system, but still typeing as O Negative in tubes. What is could possilby be the problem, and what can I do to not see this problem in the future?

Generally this occures due to the type of reagent being used and which D clones are present in them. We currently use the Ortho Provue and do have this issue occasionally but they have an interpretation guide for IGG cards on what to do if the reaction is less than 2+

This past March we had a patient come thru the Emergency Department who was pregnant and spotting. A Type and Rh were performed at that time with a result of O Negative using the conventional tube system. She is now back in the facility delivering but testing as O Positive in the Gel system, but still typeing as O Negative in tubes. What is could possilby be the problem, and what can I do to not see this problem in the future?

It could well be that the lady is a Weak D Type 2, which gives particularly weak reactions (or even another Weak D Type that also gives very weak reactions).

Were it me, until this is proved one way or 'tother, I would err on the side of calling her D Negative and give her anti-D immunoglobulin if her baby is D+.

I vote that people should either be clearly D+ or clearly D-. They should not be allowed to be a Weak or Partial D!!!!!!!!!!!!!

This, however, could put me out of a job, so I'll think about that one!

:eek::eek:

Upon subsequent recollect, she is still weakly positive (1+) in gel, but negative in the tubes although her weak D is a +/= reaction. My thoughts are in line with Malcolm and we will consider her a D negative for Rhogam purposes.

We just had this with the Echo. Specimen in October was O pos and specimen in November of O neg, both run on the Echo. In October it gave a ? for the Anti-D. Tube testing had her at weak positive. Review of patient's chart by the MD office showed discrepancies in the past. We recommended Rh Immune Globuiln and change the O pos to an O neg.

Btw, it was the same lot of Anti-D on the Echo for both tests. Not sure what happened.

Edited November 17, 200915 yr by clmergen
Afterthought

This past March we had a patient come thru the Emergency Department who was pregnant and spotting. A Type and Rh were performed at that time with a result of O Negative using the conventional tube system. She is now back in the facility delivering but testing as O Positive in the Gel system, but still typeing as O Negative in tubes. What is could possilby be the problem, and what can I do to not see this problem in the future?

The gel system is much more sensitive than the tube system. We also find that some patients we typed years ago via tube method are now proving to be Rh pos in gel. Most times your gel reaction will be 2+ or less, but not always!

I agree with previous posts....always better to err on the side of caution in regards to rhogam administration. It is much better to give rhogam even if it is not needed then to not give it when it is needed. We, however don't do it. We trust the results of our Provues (we have 2) and the gel system.

I was very glad to find this thread. We have recently gone live with the ProVue, and have run across a similar scenario. An OB patient typed Rh Pos by automated gel, but her retype by tube was negative (immediate spin). Because of the discrepancy, the tech carried it through to Coombs phase, and lo and behold! she came up as weak D positive. Although I had always viewed "weak D" as needing AHG to be demonstrated, the new method (gel technology) may have us rethinking this paradigm.

Our institution treats weak D patients as Rh negative when it come to receiving blood or products (including Rhogam), but they would be considered as Rh positive if donating blood. We explain it to our techs in terms of always trying to avoid stimulating the production of anti-D.

Julie H.

Since this patient is an OB, her baby was typed from the cord blood. The baby typed as A+ with a negative DAT, while the mother is O=. Fetal screen (rosette) was a weak 1+ reaction, with a negative DAT. We feel that this mother is suffering from a fetal bleed, KB stain/flow sent off to our reference.

With the baby having a negative DAT, the positive rosette test could be due to the weak D. If you administer Rh immunoglobulin, one way to resolve this is to test her for D and rosette test in 4-6 months.

The rosette test result should be considered an invalid result due to the positive weak D typing on the maternal sample. Your follow-up actions are correct though, the K/B/flow will determine if there was a significant fetal-maternal bleed (without interference from the maternal weak D).