Question

The laboratory requisition indicates that you are to collect a venous blood specimen for hematology testing, serum chemistry testing, and coagulation studies. What is the proper order of collection for these tubes?

Answer 1

The correct order of collection for a venous blood specimen is first the coagulation tube, followed by the serum tube, and finally the hematology tube to prevent cross-contamination and ensure accurate test results.

Step-by-step explanation:

The proper order of collection for tubes when collecting a venous blood specimen for hematology testing, serum chemistry testing, and coagulation studies is based on the Clinical and Laboratory Standards Institute (CLSI) guidelines. Typically, the order of draw is as follows:

1. Coagulation tube (light blue top), which is used for coagulation studies and contains sodium citrate.
2. Serum tube (red or gold top), which is used for serum chemistry tests and contains a clot activator or gel for serum separation.
3. Hematology tube (lavender or purple top), which contains EDTA and is used for hematology testing including complete blood counts.

Adhering to this order is crucial to prevent cross-contamination of additives between tubes which could affect the test results.