Resolving crossmatch incompatibilities always varies from case to case. The systematic approach is essential to prevent missing out on any findings. This is an algorithm encompassing a systematic approach to resolving incompatible crossmatches derived based on experience obtained from dealing with various spectra of immunohematology cases in a tertiary care center [Charts 1 and 2]. The main causes of incompatible crossmatches can be classified into sample related, technical issues, and true incompatibility due to immune etiology. Blood Sample related factors causing cross match incompatibilities include contaminated sample, incompletely clotted sample, lysed or lipemic, samples taken from IV lines via which drugs are being administered, samples taken from the surgical site or samples showing rouleaux formation. Technical factors can be (1) DCT-positive patient red cells entering the reaction chamber, (2) incompletely centrifuged sample, (3) incompletely centrifuged gel card, and (4) wrong incubation temperature. True incompatibility due to immune causes include intake of drug like daratumumab, positive Direct Antiglobulin Test (DAT) of donor red cell or presence of alloantibody or autoantibody in patient [Figure 1].
Flowchart 1.
Pan reactivity
Flowchart 2.
Varying grades of reaction
Figure 1.
Algorithm to resolve incompatible cross match due to immune cause
Pattern: Some red cell panels showing positive reaction and some red cell panels showing negative reaction with patient serum
Pan reactivity: All red cell panels showing positive reaction with patient serum and the grade of the reaction can be equal or varying.
Conflicts of interest
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Funding Statement
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