Incompatible crossmatch following nonreactive antibody detection test. Frequency and cause.

In order to determine the frequency and cause of an incompatible crossmatch found in specimens for which the antibody detection test was nonreactive, 261, 136 crossmatches performed on 116,278 patient samples from approximately 46,000 different patients were reviewed. One-hundred and one patients were identified whose sera were incompatible in at least one crossmatch following a nonreactive antibody detection test. The cause of the incompatibility was determined in 69 of these. Incompatibility was detected only after 37 degrees C incubation and/or after the antiglobulin phase in 36 (52%). Incompatibility was detected after an immediate-spin and/or incubation at room temperature in 33 (48%). Serologic evaluation did not identify the cause of the incompatibility in 16 of the 101 patients. In eight of these 16 the incompatibility was noted only after 37 degrees C incubation and/or after the antiglobulin phase. Detailed serologic evaluation was not performed on 16 of the 101 patients (all of whose sera were incompatible with only 1 donor unit). In 12 of these 16, the incompatibility was detected only after the antiglobulin phase.