Looking for feedback about transfusing DAT positive donor units. It seems like these red cells would have decreased cell survival, but I am having trouble locating anything that speaks to the subject. Anybody have info on this?

Obviously, it depends upon how strong is the DAT, and by what the DAT is positive (IgG?,/ IgM?, IgA, C3c, C3d or a combination) as to how long the red cells will last in the recipient's circulation, and, to a certain extent, the underlying pathology of the recipient, but, in most cases, although there may be a reduction in the cell survival, as far as I know, there is nothing in the literature that points to the fact that the transfused red cells will be rapidly cleared from the circulation. It may be that the patient requires another "top-up" slightly earlier than would otherwise be necessary, but, as most patients only ever receive one episode of transfusion, to get them over a time of low Hb, whilst their own bone marrow tops up their circulation, this often does not matter.

Evidence that this is true comes from the fact that an enormous number of units have been transfused to patients following electronic issue, some of which must have been DAT+, with no adverse sequelae.

Thanks- the positive DAT was found at extended crossmatch so it reasons to stand that we will not be able to transfuse this to anyone requiring extended crossmatch and had it been selected for a patient with electronic or IS crossmatch it would have been transfused. But now that we have identified this unit as having a positive DAT is further action necessary? Is there any reason to avoid issuing this unit?

There is no reason not to issue DCT + as Malcolm stated but we are not issuing. We are on ABSC and AHG cross match so we get this unit incompatible in coombs and discard it.

Whenever we found these units we did not transfuse them.

same like David..if when we found them we notify blood center and send them back. We do not transfuse them.

We have had a few instances of this in the past, and get full credit from the American Red Cross for these units. We do not draw our own donors.

:):)

We do not use them if we detect them. We return them to the blood center for credit.

Same here...Red Cross is good about crediting us for these units.

Ah, but that is if you detect them (we get ours sent back to us too, and we reimburse our hospitals).

What I was saying is that, there MUST have been DAT+ units transfused to patients following electronic issue (which would not have been detected), and I have yet to see anything in the literature that says patients react adversely to these.

Does anyone know of any studies on what might cause someone to have a positive direct Coombs test and not have a disease process going on (at some level)? That is as much a concern to me as the fact that the cells might have a shortened life span.

Same here...Red Cross is good about crediting us for these units.

Same for us.

If we find them, we send them back to our supplier with no problem. But as Malcom has said, in this day of electronic and immediate spin crossmatches, we must unknowingly transfuse DAT+ units frequently without incident. Consider, too, that despite having RBCs coated with IgG and/or complement, the donor had a high enough hemoglobin to donate in the first place, so the autoantibody can't be doing too much damage to his/her cells.

Does anyone know of any studies on what might cause someone to have a positive direct Coombs test and not have a disease process going on (at some level)? That is as much a concern to me as the fact that the cells might have a shortened life span.

I have to admit that this is something I've wondered about, too. There was a small study done, in Israel I think, to see if apparently healthy blood donors with pos DATs developed some sort of cancer/hematological disorder at a later time. It was published in Transfusion (Vol.49, Issue 5, May 2009, pgs 838-842). The followup on this small group of people did, in fact, find that there is an increased risk. Their conclusion statement: "There is evidence of a significantly increased risk of cancer, especially hematologic malignancies, among blood donors with a positive DAT even within a short follow-up period." Interesting study.

Does anyone know of any studies on what might cause someone to have a positive direct Coombs test and not have a disease process going on (at some level)? That is as much a concern to me as the fact that the cells might have a shortened life span.

I recall reading a case of an elderly British lady who imbibed gin and tonic daily developing a positive DAT. Back then the tonic water had higher levels of quinine.

Ah, but that is if you detect them (we get ours sent back to us too, and we reimburse our hospitals).

What I was saying is that, there MUST have been DAT+ units transfused to patients following electronic issue (which would not have been detected), and I have yet to see anything in the literature that says patients react adversely to these.

NBS policy now says that any unit found to be DAT+ is Ok to transfuse - don't think they can return them anymore!

We had one sent back last week - with the NHSBT Consultant's blessing!

:threaten:What can I say but we're harder up North! Our patients can take it...

:threaten:What can I say but we're harder up North! Our patients can take it...

Love it!!!!!!!!!

I think, in this case, the only reason we got it back was because they got the Consultant involved. I'll say no more!

I think, in this case, the only reason we got it back was because they got the Consultant involved. I'll say no more!

The other reason Malcolm as far as I know is that I haven't seen any NHSBT policy that says that we can't send them back. If you do IAT cross-matches as a routine and it is positive against a unit most BMS will reject the unit. With electronic issue what you don't see you don't know about, a bit like enzyme only antibodies - but that is another topic altogether.

Steve

:)

Yes that is true Malcolm but I think once we know we should not transfuse these units.

If you think about antibody to low frequency antigen, patient may have this antibody but doesn't get detected until we do full crossmatch or one of the screening cells pops up with this antigen. we will never identify this antibody unless patient comes back with hemolytic reaction/delayed hemolytic reactions.

I have not seen any current information published. As far as I know it is not harmful to the patients for reasons Mr. Needs has stated. We did accept them back at the blood center and we did have our reference lab investigate. Not for reasons associated with transfusing the unit but to contact the donor for their health considerations. Same may be on meds or herbs that cause the pos DAT or maybe it has some other clinical meaning they may want to contact our Medical Director or their personal physician.