We have a new to us, 36 year old Female OB that has a history from the Dr office of being A Neg. We did her Rh by gel and got Pos...repeated on new draw by different Tech, also got Pos. Then did by tube thru Du and got Neg. Any thoughts or suggestions as how to proceed? We are checking on more history and I'm calling the consultative services at the blood center...don't find anything in the Ortho literature I have. Thanks, Kay

We have a new to us, 36 year old Female OB that has a history from the Dr office of being A Neg. We did her Rh by gel and got Pos...repeated on new draw by different Tech, also got Pos. Then did by tube thru Du and got Neg. Any thoughts or suggestions as how to proceed? We are checking on more history and I'm calling the consultative services at the blood center...don't find anything in the Ortho literature I have. Thanks, Kay

I'm not saying it is this, but it could be a partial D that is not detected by the anti-D clones used in your tube anti-D, but is picked up by the clones of anti-D used in your column agglutination technology (CAT).

It could also be that the CAT is considerably more sensitive than tube technology, and that you are detecting a very weak, Weak D antigen, such as Weak D type 2, 3 or 4.

:confused::confused:

We had the same scenario earlier this spring (that is how I found this site in fact). Gel testing resulted in a rh positive while tube results were rh negative. Ours was a situation of previous history at other hospitals indicated rh negative while our lab continually had rh positive results in gel. I contacted both facilities with previous records for this patient and determined both were using tube methodology at the time. We redrew the patient and repeated our testing. Additionally we submitted a sample to our reference lab and had them figure out what they could. Bottom line was that gel testing is more sensitive than the tube method in this case. Patient was identified as a partial D. We confered with the OB/Gyn (it just happens to be one of the midwive's daughters-in-law ) and decided RhIg would be an acceptable precaution. Conservative stance? Yes! AM I satisfied with the outcome? For now. As more information becomes available on D and sensitivities increase we will continue to have situations such as this. I try to remember that mom is the "recipient" in a potential transfusion and the fetus is the potential "donor". Just helps me keep things straighter in my mind I guess.

If you're using ortho gel technology I have heard that a positive DAT can sometimes affect the D typing! Does the patient have a pos DAT?

If you're using ortho gel technology I have heard that a positive DAT can sometimes affect the D typing! Does the patient have a pos DAT?

I think that you are referring to a couple of NEQAS exercises, where the D- red cells were deliberately made DAT+. Ortho came to one of our Transfusion Advisory Group meetings and explained that thhese reactions were to do with the % of albumin in their anti-D reagents, and that this would not happen with a true patient's sample.

I leave you to decide whether or not to believe this explanation!

:rolleyes::rolleyes:

I make it a general rule to be highly suspicious of anyone selling me anything!!!

I make it a general rule to be highly suspicious of anyone selling me anything!!!

Fluffy, you are highly suspicious of anyone anyway!!!!!!!!!!!!!!!!!!!!!!!!!!!

(That'll teach you to call me infamous!!!!!!!!!!!!!).

LOL, LOL!

:nana::nana:

I guess I'd better not make any comment on your other post about you being THE original A1 then...

I guess I'd better not make any comment on your other post about you being THE original A1 then...

Touche!

:D:D:D:D

Ok so back on topic!

Just had a chat with the reference lab about positive DATs causing problems with D grouping when using Ortho, they say they see these referrals on a regular basis. Referred either as 'D??' or changed from 'historical D- to D+' this time.

Usually most turn out to have a positive DAT & are actually D-.

Worth a try doing a DAT to see if it will help resolve the situation, especially since your tube group was D-.

Ok so back on topic!

Just had a chat with the reference lab about positive DATs causing problems with D grouping when using Ortho, they say they see these referrals on a regular basis. Referred either as 'D??' or changed from 'historical D- to D+' this time.

Usually most turn out to have a positive DAT & are actually D-.

Worth a try doing a DAT to see if it will help resolve the situation, especially since your tube group was D-.

Agreed.

We have come across this situation as well, since we use Gel for our first type and tube for the 2nd confirmation type. There was an article in March 2008 Transfusion by Judd in which he addresses this issue. He suggests that the final interpretation of Rh type be negative if if you get a weak to 1+ by tube and a 2+ by Gel. Our medical director made the decision that this would be the approach we would take. We have been doing it now for almost 2 years. It was a bit confusing in the beginging, but blood bank staff is very comfortable now with the policy. We also developed an information sheet for physicians and nursing that explained why there is a difference in Rh type depending on hte technique used. We shared it with the LD staff as well as put it on our intranet. Now when we get a phone call about the discrepancy between our type and the pre natal type we refer them to the info sheet.

OK, I'm confused...why would you call someone Rh negative if you got agglutination in your immediate spin tube test?

We also have a couple of these sent to us each month. If they call before sending the sample we will remind them to DAT test in Gel before sending. MOST of these are due to + DAT. (at least here they are) Do those of you using Gel for ABO/Rh see many problems due to Gel? As a side thought, it surprises me how many hospitals use Gel and the ORTHO person training them didnt show them how to perform Gel DAT. Had a small hospital send us 3 samples one morning with positive screens. (they usually send us 2 a month) Called them before starting these and found out all three were 1+ on cell one. Told them to do DAT on that cell and guess what.... yep 1+.

If the tube testing was through AHG, wouldn't it have deteceted the pos DAT?

Then did by tube thru Du and got Neg.

I'm not very familiar with gel, but if the pt DAT was positive wouldn't it have been detected with the tube testing at AHG?

I have researched this quite a bit as I am considering going to the ABD gel card from the Ortho tube reagents. Even within the same company, different clones are used for different methodology. If we switch we do run a slight risk of changing RH types. We have decided to leave any previously negative OB patients as negative just to be safe so that they get Rhogam. This may also happen from one facility to another depending on methodology.

We have a new to us, 36 year old Female OB that has a history from the Dr office of being A Neg. We did her Rh by gel and got Pos...repeated on new draw by different Tech, also got Pos. Then did by tube thru Du and got Neg. Any thoughts or suggestions as how to proceed? We are checking on more history and I'm calling the consultative services at the blood center...don't find anything in the Ortho literature I have. Thanks, Kay

If I understand correctly using Ortho Gel (anti-D clone MS201) the cells are D positive; using Ortho BioClone anti-D (MAD-2 + human polyclonal anti-D) the cells are negative IS and IAT. The D type could be DHAR.

See Westhoff C. Transfusion 2007; 47:17S-22S or Judd et al Immunohematology 2005; 21:146-148.

We had a similar situation but the conflict in Rh result was between the patient history at their doctors office and our current Rh typing using tube method. The historic Rh was Neg and our current Rh was positive; repeated on a second specimen one day apart. The patient, an L&D pt., was given RhoGam at 28 weeks gestation. The patient was now in for delivery when we acquired our findings.

One interesting aspect of this case was the visual texture of the actual IS Rh Pos agglutinate. It had a somewhat rubbery or mucoid visual texture as we manipulated the tube upon reading. I beleive that this was do to the binding of the concentration of RhoGam to exposed D antigen sites. This binding would prevent our D reagent from binding to these sites causinig an incomplete or meshed agglutinate which would be limitted in it's ability to expel water potentially causing the mucoid appearence; and it did not have the more crisp texture and the clearer suppernatent background.

The other interesting aspect of this case is that the patient physician still wanted the additional RhoGam that she ordered. Error on the side of caution; excellent chioce. But one complication that could occur with giving RhoGam to an Rh-Pos L&D patient would be that the Blood Bank staff would have to be alert to any orders for FMHSC using D antigen as the detection method. With this case and other like L&D cases that are encountered we need to perform KHB staining to detect any fetal maternal hemorhage. The reason I say this is because I can see the patient physician ordering an FMHSC and our staff performing the test and giving out a false Neg result do to the RhoGam binding D antigen sites and preveneting binding of the D reagent used causing the Rosette count to fall to a negative interpretation or not appearing at all; ultimately causing the generation of an allo-D in a positive D mosaic mother once the in-vivo RhoGam was overwhelmed or depleted which may not be seen until the next pregnancy and all sorts of problems to follow in a worst case situation. Of course this would be assuming that the circulating concentration of the fetal cells in the maternal system exceeded the life of that of the administered RhoGam and remained circulating long enough at a concentration capable of sensitizing the mother. I hope this helps some.

Edited August 1, 201015 yr by rravkin@aol.com

Pos DAT flashed through my mind before a weak D expression of some sort...

just percentages in my own experience, I guess...

I was hoping you may be willing to share your info sheet you made for the physicians and nursing staff.