Compatibility Testing (Crossmatch)

This essential practical topic covers compatibility testing (crossmatch), the final procedural check before issuing blood for transfusion to a patient in Zambia. Students will learn the difference between the short (immediate spin) crossmatch, which primarily checks for ABO incompatibility, and the complete (antiglobulin) crossmatch, which detects other clinically significant antibodies. The curriculum explains the modern 'Type and Screen' (T&S) strategy, where a full antibody screen substitutes for a complete crossmatch in most cases, and the specific clinical situations where a full crossmatch remains mandatory (e.g., patients with known antibodies, neonates). A detailed, step-by-step procedure for performing both saline and BSA complete crossmatches is provided, including the use of Coombs Control Cells. Students will also learn how to grade and interpret agglutination reactions. Furthermore, the topic guides learners in investigating a positive crossmatch when the antibody screen is negative, considering causes like ABO incompatibility, antibodies to low-frequency antigens, or a positive Direct Antiglobulin Test (DAT) on donor cells. For Zambian university and college students, mastering crossmatching techniques and logic is a critical competency that directly impacts patient safety and is a core requirement for professional practice in any hospital blood bank.