During which scenario is a 'crossmatch' sample collected?

The scenario in which a 'crossmatch' sample is collected primarily pertains to ensuring compatibility between a donor's blood and a recipient's blood before a transfusion. This process is crucial as it helps prevent adverse reactions that could occur if incompatible blood types are mixed in the patient’s system. The crossmatch test assesses the recipient's antibodies against the donor's red blood cells, confirming whether the transfusion can proceed safely.

In this context, when preparing for blood transfusions, particularly in medical settings where allergic reactions or hemolytic reactions may pose significant risks, the crossmatching process is indispensable. It establishes a critical safety protocol to protect patients from potential complications related to transfusion.

Other scenarios, such as those mentioned, do not involve the procedure of crossmatching. Collecting a sample before drawing plasma for testing is generally related to specific tests or analyses, while preparing for scheduled surgery may involve different preoperative assessments. Monitoring blood sugar levels is entirely distinct from blood transfusion protocols and does not engage the crossmatching process.