Equivalent Methods for Compatibility Testing (12/14/84)

December 14, 1984


FROM:      Acting Director, Office of Biologics Research and
           Review

SUBJECT:   Equivalent Methods for Compatibility Testing

TO:        All Registered Blood Establishments


Background:

In response to the large public interest generated by several
publications which suggested that the antiglobulin crossmatch was
unnecessary in many situations, the FDA sponsored a workshop in
December 1981 on "The Role of Compatibility Tests."  The Blood
Products Advisory Committee in attendance at this workshop
recommended revising 21 CFR 606.151 to permit alternative methods
for the antiglobulin phase of the crossmatch.  We are in
agreement with this recommendation but proposals to chance the
current rules have not yet been published in the Federal
Register.

Recognizing both the significant cost savings that the chances
proposed by our Advisory Committee would effect, and considering
the public awareness of FDA's direction (Garraetv, G.,
Transfusion: 22, p. 169, 1982), we have informed FDA inspectors
that in many situations the "type and screen" procedure is an
acceptable alternative to crossmatching. 

Equivalent Procedures:

We consider compatibility procedures which include the following
elements as equivalent to the procedures prescribed in 21 CFR
606.151 for the purpose of preparing blood for transfusion:       


(a)  A method of collecting and identifying the blood samples of
     recipient using donors to ensure positive identification.

(b)  The determination of the ABO and Rh groups of the donor and
     recipient using licensed blood grouping sera or their
     equivalent.

(c)  Antibody detection tests that will demonstrates significant
     alloantibodies, by the active at 37 C in the serum or plasma
     of a previously transfused or previously pregnant donor.

(d)  The testing of the recipient's serum for unexpected
     alloantibodies, by the antiglobulin technique or an equally
     sensitive method that will demonstrate significant
     antibodies reactive with the donor's cells at 37 C.

(e)  Procedures to expedite transfusions in life-threatening
     emergencies and, if applicable, procedures for testing blood
     for neonatal transfusions and autologous transfusions.

You will note that the above requirements permit the substitution
of an adequate antibody screening test (d) for the major
crossmatch.  Such procedures have been very widely applied and,
as reflected by the new AABA Standards, have been successful in
assuring safe transfusion.  We will continue to evaluate
questionable crossmatch practices on a case-by-case basis.



     Elaine C. Esber, M.D.