[When A is not A anymore: problems and pitfalls with blood group typing]

Area of Science:

• Immunohematology
• Transfusion Medicine

Background:

• Accurate blood group typing is essential for safe blood transfusions.
• While typically straightforward, blood group determination can be complicated by various factors.

Purpose of the Study:

• To provide clinicians with a foundational understanding of blood typing complexities.
• To highlight potential challenges and emphasize the importance of accurate diagnostics.

Main Methods:

• Standard blood group determination includes ABO, Rhesus, and Kell systems.
• Direct Coombs test and antibody screening are performed to detect irregular antibodies.
• Bedside testing is crucial for preventing transfusion errors.

Main Results:

• Patient-related factors, such as irregular antibodies, complicate immunohematology.
• Medications like daratumumab significantly increase laboratory complexity.
• Chimerism can arise from massive transfusions or stem cell transplantation, altering blood groups.

Conclusions:

• Rare blood groups, diseases, and iatrogenic factors can cause difficulties in blood group determination.
• Early and close collaboration with transfusion medicine specialists is vital for clinicians facing diagnostic challenges.
• Preventing errors in patient identification, samples, results, and preparations is paramount to avoid incompatible transfusions.