Which factor is commonly associated with hemoconcentration?

• A. Prolonged tourniquet time.
• B. Rapid blood draw with small tourniquet pressure.
• C. Capillary collection.
• D. Immediate serum separation.

Answer: (A)

Hemoconcentration means the blood sample becomes more concentrated because plasma water is reduced or redistributed, so formed elements and proteins appear higher. In phlebotomy, leaving the tourniquet on too long causes venous stasis and increased hydrostatic pressure in the veins. This pushes fluid out of the intravascular space and into surrounding tissue, concentrating the blood sample. That’s why prolonged tourniquet time is commonly associated with hemoconcentration.

Keeping the tourniquet on briefly while you locate a vein minimizes this effect, and using proper technique helps maintain normal plasma volume. Rapid blood draw with a properly applied, not overly tight tourniquet decreases the chance of concentration changes. Capillary collection can introduce variables like tissue fluid admixture, but it’s not the classic cause of hemoconcentration. Immediate serum separation, by itself, helps prevent issues after collection rather than causing the concentration change in the drawn sample.