Laboratory ProceduresDifficulty 2/5
Which tube is appropriate for a complete blood count?
- AA sodium citrate tube, which is filled to the marked ratio line
- BA lithium heparin tube, which prevents clotting without cell damage
- CAn EDTA tube, which preserves cell morphology for haematology
- DA plain serum tube, which allows the sample to clot before analysis
Show answer and rationale
Correct: C. EDTA is the anticoagulant of choice for haematology because it preserves cell morphology. Heparin distorts staining, serum tubes clot, and citrate is for coagulation testing.
- B — Heparin interferes with Romanowsky staining of blood films.
- D — A clotted sample cannot give a cell count.
- A — Citrate dilution is designed for coagulation assays.