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Undetermined Rh in Meditech


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I am responsible for building the Blood Bank module in Meditech Magic and am having trouble with the Rh Undetermined typing. Does anyone have any suggestions of the best way to get Meditech to properly evaluate the blood type truth table to correctly identify Rh Undetermined without the need for including the weak D testing on every ABO/Rh test ordered? We are due to go live in late February and I am trying to perform the computer validation for the Blood Bank module but am unable to continue past the ABO/Rh validation.

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  • 3 weeks later...

Hi Wolvrine.

I do not know what Meditech Magic is but I assume it is a BB LIS system. While it seems that an RhD testing algorythm should be pretty simple, it is actually pretty complex as each institution should decide and impliment their own testing protocol. The type of testing done can even vary in the lab depending on the sample type (Donor, Blood recipient, cord blood etc).

I cannot see where you are from in your profile but differnt populations can and should have different testing performed depending on the incidence of D variants and weak Ds. Ther are also country specific guidelines and regulations that specify the number and specificities of reagents used that may need to be complied with.

As an example, Australian operational transfusion labs generally (but not always) use 1 Anti-D reagent that is DVI negative. They will often (but not always) use a second Anti-D in the check group. Donor group testing is done by the Australian Red Cross and they use 2 Anti-Ds. One is DVI negative and the other DVI positive. If both reagents concure the result is accepted. If they disagree further testing is done to clarify the group (usually a DVI variant but not always.

I think a LIS needs to be flexible enough for a lab to choose the testing algorythm and use appropriate decision tables based on the algorythm, specificity and sensitivity of the reagents used and the incidence of weak Ds and variants in that population.

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We also are using Meditech-Magic at our hospital. I was not responsible for setting up the truth tables etc. but I do know that if we need to do a weak D tedt (formerly Du) we add the test to the patient's accession number and result the test. We only do the weak D test on babies of Rh negative mothers to determine RhoGam status. We do not use the terminology 'undetermined Rh'-I am curious why that would be used. Does 'undetermined Rh' get reported out on some of your patients? Is this a common practice?

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Give me your email address or your phone number and we can get in contact and I'll show you our Meditech Magic build for D Indeterminate and Weak D - the tests can be waiting in the result colum (normally answered with "NP") and only used as needed.

575-521-2202 or carolyn.swickard@lpnt.net

Edited by carolyn swickard
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We also are using Meditech-Magic at our hospital. I was not responsible for setting up the truth tables etc. but I do know that if we need to do a weak D tedt (formerly Du) we add the test to the patient's accession number and result the test. We only do the weak D test on babies of Rh negative mothers to determine RhoGam status. We do not use the terminology 'undetermined Rh'-I am curious why that would be used. Does 'undetermined Rh' get reported out on some of your patients? Is this a common practice?

Yes I am curious as well, you can't possibly think to leave an RH as undetermined as to the outcome. The only issue we have is that the RH control is required on all ABP to rule out pan agglutination. We only do weak D on our infants or Mom's with a pos fetal screen.

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Yes I am curious as well, you can't possibly think to leave an RH as undetermined as to the outcome. The only issue we have is that the RH control is required on all ABP to rule out pan agglutination. We only do weak D on our infants or Mom's with a pos fetal screen.

Well, actually, we do too at the Reference Laboratory.

It's on the grounds that we never believe anyone else's results but our own, and if the patient has been recently transfused and we get a mixed-field reaction with anti-D, we will report it as "D??".

:redface::redface::redface::redface::redface:

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We have also had neonates who were transfused in utero who end up with undetermined types, sometimes both the ABO and Rh. We had one such infant who may actually have acheived a transplant from the blood we transfused in utero. His mother had strong anti-D and anti-C and the blood we first got from the cord in utero was O positive. After birth, he was O negative and remained so for the two years we followed him. What do they say about unintended consequences?

Edited by adiescast
Incorrect term
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We have also had neonates who were transfused in utero who end up with undetermined types, sometimes both the ABO and Rh. We had one such infant who may actually have acheived a transplant from the blood we transfused in utero. His mother had strong anti-D and anti-C and the blood we first got from the cord in utero was O positive. After birth, he was O negative and remained so for the two years we followed him. What do they say about unintended consequences?

Is the blood used for an IUT not irradiated to prevent this (and TA-GvHD) happening???????????

:eek::eek::eek::eek::eek:

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We also are using Meditech-Magic at our hospital. I was not responsible for setting up the truth tables etc. but I do know that if we need to do a weak D tedt (formerly Du) we add the test to the patient's accession number and result the test. We only do the weak D test on babies of Rh negative mothers to determine RhoGam status. We do not use the terminology 'undetermined Rh'-I am curious why that would be used. Does 'undetermined Rh' get reported out on some of your patients? Is this a common practice?

The only reason that I can see for reporting an undetermined Rh on a baby is if the DAT is positive with a negative Rh.

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Oh yes it is. But nothing is 100% and that is the only explanation I can come up with for the child's change in blood type. Any other ideas?

Well, it is rare (extremely rare), but it could be that the child was a D Neg chimera (as a result on conjoined twins) who had fully absorbed the twin (who was D Pos) and that the maternal anti-D wiped out the D Pos clone.

This is nothing more than an unlikely, but possible, explanation.

The DNA profile from his leukocytes would be interesting, one way or the other.

:confused::confused::confused::confused::confused:

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Actually, given that scenario, the live child would not necessarily be a chimera. If there were fraternal twins present at the time of the line draw and they drew the Rh positive twin, it would explain it. That explanation would necessitate that the twin that was later absorbed was tranfused that time and that the mother absorbed the failed fetus, not the twin. It would also mean that we unnecessarily transfused the Rh negaticve twin for the rest of the pregnancy, which is unlikely, since I believe they did hemoglobin tests each time they entered the cord before they decided to transfuse. They certainly should have!

This happened several years ago and as far as I know, the child is fine, so we are not likely to get HLA types on him anytime soon.

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We went live in Meditech about a year ago. We did not use Rh undetermined in our module. We added a Du test on the cord bloods. They default as "NP". If the baby is Rh neg, we do the Du, and result it. Meditech has a pop up box that warns the type is wrong when we enter an Rh neg, with no Du result.

The reason I see for Rh undertermined is that if the baby is Du pos, we type the baby as Rh pos so the mother gets RhIG. If the baby returns when it is older, we would have to change the type because we do not Du test anything but cord bloods. A little confusing!

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