NHA Certified Phlebotomy Technician (CPT)Specimen HandlingHard
A phlebotomy technician observes that a serum specimen, which was collected an hour ago and has been sitting upright, now shows a visible layer of fibrin strands after centrifugation. Which of the following is the most likely cause of this issue?
- AThe tube was inverted too many times after collection.
- BThe centrifuge speed was too high, causing cellular disruption.
- CThe specimen was exposed to excessive light during the clotting period.
- DThe specimen was not allowed to clot completely before centrifugation.
Show answer & explanationAnswer & explanation
Correct answer: D. The specimen was not allowed to clot completely before centrifugation.
Fibrin strands in serum after centrifugation indicate that the blood did not clot completely before spinning. This often happens if the clotting time was insufficient or if the tube was not inverted adequately (for tubes with clot activators) to mix the activator.
Why the other options are wrong
- A. Excessive inversions typically cause hemolysis, not fibrin strands.
- B. High centrifuge speed primarily affects cell integrity (hemolysis) or causes poor gel barrier formation, not fibrin strands.
- C. Light exposure affects light-sensitive analytes but does not cause fibrin strands.
Fibrin Strands in Serum
The presence of fibrin strands in serum after centrifugation indicates incomplete clotting of the blood specimen, typically due to insufficient clotting time or improper mixing of clot activators.
- Prevents accurate testing.
- Requires re-centrifugation or recollection.
- Causes include short clotting time, inadequate inversion.
Memory trick: Fibrin Strands: Clotting Cut Short, Results Distorted.