What is the purpose of using a 'two-stage crossmatch' in blood transfusion?

A To detect ABO incompatibility
B To detect Rh incompatibility
C To detect the presence of unexpected antibodies ✓
D To reduce the risk of transfusion-related acute lung injury (TRALI)

Explanation

A two-stage crossmatch is used to detect the presence of unexpected antibodies in the recipient's plasma that could react with the donor's red blood cells.

Source

American Association of Blood Banks (AABB) guidelines
Hematology Hematology: Blood Grouping and Crossmatching Hematology: Blood Grouping and Crossmatching Medium MEDICAL Confidence: high