In vivo cross-match by chromium-51 urinary excretion from labeled erythrocytes: a case of anti-Gerbich.

We studied a patient with an alloantibody to the high-frequency red blood cell (RBC) antigen Gerbich. A nationwide search for rare Gerbich-negative blood (less than 1:45,000 donors) located only seven units, and our supply was quickly exhausted. By using an in vivo cross-matching method, we demonstrated that this anti-Gerbich did not cause RBC destruction. Regular Gerbich-positive transfusions could then proceed without hemolysis. This cross-match test was based on the determination of the urinary excretion rates of injected radioactive chromium-labeled donor erythrocytes by which it was possible to determine compatibility only 24 hr after the test was begun. The procedure provides an easy and accurate means for in vivo cross-matching of conventionally incompatible donor blood.