A medical director of a Midwestern laboratory reports that his transfusion service uses a Gel-antiglobulin (Gel-AHG) methodology to perform antibody screens and antibody identification panels. Occasionally a patient sample is encountered that has a positive Gel-AHG antibody screening test result, but when the sample is worked up to determine the causative antibody, either the antibody identification panel is completely negative, or the panel results do not fit that of any definitive pattern known to correspond to a potentially clinically significant antibody. The inquiring physician wants to know if colleagues would require that an antiglobulin crossmatch be used when crossmatching donor units for a patient who has a positive Gel-AHG antibody screen, but a negative or equivocal Gel-AHG panel workup. Would any colleagues feel comfortable crossmatching donor RBCs for such a patient using an immediate spin crossmatch?

The following responses have been submitted.

1. The Editor reports that at the USC Kenneth Norris Cancer Hospital (where he is transfusion service medical director) such a patient would be crossmatched using a Gel-AHG crossmatch. The immediate spin crossmatch is reserved for patients who have a current negative Gel-AHG antibody screen, no history of any unexpected antibodies, no history of any transfusion reactions, and no other immunohematologic abnormalities (such as a positive direct antiglobulin test). The majority of patients crossmatched at the Webmaster's transfusion service are crossmatched using an immediate spin test.

ADDENDA Aug. 13, 2003

2. A blood bank technologist in Glendale, California reports that until the reactivity described by the inquiring colleague is explained or goes away completely, his transfusion service would perform an AHG crossmatch.

3. A colleague at a small hospital in Southeastern Pennsylvania reports that they have been using a Gel-AHG methodology for three years, during which they encountering several cases for which the Gel-AHG antibody screen was positive, but the Gel-AHG panel was inconclusive. Occasionally, they have sent these specimens to a reference lab for further work-up. The reference lab typically reports that these samples contain anti-HLA or anti-HTLA antibodies. On one occasion, a monocyte monolayer assay was requested, and the results indicated that the antibody was not likely to cause clinical hemolysis. The responding colleague adds that even if they can rule out all the clinically significant antibodies, they still will select Gel-AHG crossmatch compatible RBC units for transfusion. Their local policy regarding crossmatching is that the same technology used to detect the antibody must be used when doing the crossmatch, especially if the panel was inconclusive. The reason for their local crossmatch policy is that they have encountered three "clinically significant antibodies" that were detectable by the Gel-AHG method, but not by a tube method; these antibodies were anti-D, anti-E and anti-Jk(a).

ADDENDA Aug. 14, 2003

4. A colleague in North Carolina reports that they perform about 2,000 antibody screens per month. Several each month have a positive screen and negative or inconclusive (all clinically significant r/o) panel. The next step that they do is a LISS-AHG screen. If the LISS-AHG screen is negative, they still do an AHG crossmatch in Gel-AHG and in LISS-AHG. On a rare occasion, an antibody is demonstrated in LISS-AHG that was not in Gel-AHG. If crossmatches are incompatible, the next step is a LISS panel. Their approach is summarized as follows "Better safe than sorry".

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Ira A. Shulman, MD
CBBS e-Network Forum Editor & Moderator