- A technician is processing specimens from a patient with suspected multiple myeloma. The physician has ordered both routine chemistry tests and serum protein electrophoresis (SPEP). After standard centrifugation, the serum appears unusually viscous and flows slowly when pipetted. How should this observation affect the processing protocol?
Answer: Process the specimen normally but document the viscosity observation and alert the laboratory supervisor about potential paraprotein presence
When processing specimens from patients with suspected multiple myeloma, you need to understand that this cancer affects plasma cells, which can produce abnormal proteins called paraproteins or monoclonal proteins. These proteins can make serum unusually thick and viscous, creating a condition called hyperviscosity syndrome.
The correct approach is B - process normally while documenting the viscosity and alerting your supervisor. Viscous serum is a clinically significant finding that could indicate paraprotein presence, which is exactly what the SPEP test is designed to detect. Your observation provides valuable diagnostic information that must be preserved and communicated to ensure proper interpretation of results.
A is incorrect because re-centrifuging at higher speeds won't reduce viscosity caused by paraproteins and could damage cellular components or create artifacts. C is wrong because diluting the specimen would alter protein concentrations and invalidate both chemistry results and the critical SPEP analysis - you'd be destroying the very evidence the physician is looking for. D is incorrect because warming might temporarily reduce viscosity but could denature proteins, compromise specimen integrity, and create inaccurate results.
Key strategy: When you encounter unusual specimen characteristics in phlebotomy, especially with specific disease contexts like multiple myeloma, your first instinct should be to preserve the specimen's integrity and communicate your observations. Never alter specimens through dilution, extreme temperatures, or excessive processing - these changes can destroy diagnostically important information. Document everything and involve your supervisor when abnormalities align with suspected conditions.
- During centrifugation of coagulation specimens, a technician observes that the platelet-poor plasma (PPP) in several sodium citrate tubes appears slightly turbid rather than clear. The centrifuge settings used were 2000 RPM for 10 minutes. The specimens were collected properly with correct 9:1 blood to anticoagulant ratio. What adjustment should be made to achieve proper PPP preparation?
Answer: Perform a second centrifugation at 3000 RPM for 15 minutes to achieve the required platelet count reduction
Platelet-poor plasma for coagulation testing requires platelet counts <10,000/μL. Turbid plasma indicates insufficient platelet removal. A second centrifugation at higher speed (3000 RPM) for longer time (15 minutes) is the standard method to achieve proper PPP. Option A may be insufficient for complete platelet removal. Option B uses inadequate force for effective platelet sedimentation. Option D unnecessarily transfers specimens and uses suboptimal settings, risking contamination and incomplete platelet removal.
- A phlebotomy technician is processing STAT specimens and needs to centrifuge tubes containing different additives simultaneously. The specimens include: 2 EDTA tubes for CBC, 1 sodium citrate tube for PT/PTT, 2 SST tubes for chemistry panel, and 1 heparin tube for STAT glucose. What is the most appropriate centrifugation strategy?
Answer: Centrifuge the heparin and citrate tubes immediately at 2500 RPM for 15 minutes, do not centrifuge EDTA tubes
EDTA tubes for CBC should not be centrifuged as CBC testing requires whole blood analysis. For STAT processing, plasma tubes (heparin for glucose, citrate for coagulation) can be centrifuged immediately at appropriate settings. SST tubes require 30-minute clotting time before centrifugation, which delays STAT results. Option A incorrectly includes EDTA tubes. Options B and C use suboptimal settings or cause unnecessary delays for STAT testing.
- A laboratory's centrifuge maintenance log indicates that the rotor was last balanced 6 months ago, and recently technicians have noticed increased vibration during operation. Today, after centrifuging a full load of specimens at normal settings, several tubes show incomplete separation despite adequate processing time. What is the most likely relationship between these observations?
Answer: Rotor imbalance reduces effective centrifugal force distribution, causing inconsistent separation across specimen positions in the centrifuge
An unbalanced rotor creates uneven force distribution, causing some specimens to experience inadequate centrifugal force while others may be over-processed. This results in inconsistent separation quality across the rotor positions. The vibration is a symptom of the imbalance. Option B is incorrect because vibration doesn't necessarily indicate motor speed reduction. Option C is incorrect because heat buildup from imbalance wouldn't significantly affect gel barriers. Option D is incorrect because rotor imbalance doesn't trigger brake systems.
- During routine processing, a technician places six plasma tubes in a centrifuge and notices that after centrifugation at 2500 RPM for 15 minutes, three tubes show clear separation while three others have a cloudy interface between plasma and cellular components. All tubes were collected using the same technique and processed simultaneously. What should the technician do next?
Answer: Re-centrifuge only the three cloudy tubes at the same settings for an additional 5 minutes
When some tubes show incomplete separation while others are clear, the most appropriate action is to re-centrifuge only the affected tubes at the same settings for additional time. This approach avoids over-processing the properly separated specimens while addressing the incomplete separation. Option A risks over-centrifuging the properly separated tubes. Option B is incorrect because cloudy interfaces indicate incomplete separation that can affect test results. Option D is incorrect because improper balancing would typically affect all tubes or cause operational issues.
- A new phlebotomy technician is training on centrifuge operations and asks about the difference between processing tubes for routine chemistry versus therapeutic drug monitoring (TDM). Both use SST tubes, but TDM specimens require special handling. What is the critical difference in centrifugation protocols for TDM specimens?
Answer: TDM specimens require the same centrifugation protocol as routine chemistry, but must be processed within specific timing windows
TDM specimens use the same SST tubes and centrifugation protocol as routine chemistry tests. The critical difference is timing - TDM specimens must be collected and processed within specific time windows relative to drug dosing to ensure accurate peak or trough levels. Option A is incorrect because drug-protein binding isn't affected by centrifuge speed. Option B is incorrect because standard centrifugation temperatures are appropriate for most drugs. Option C is incorrect because SST tubes still require clotting time before centrifugation.
- A phlebotomy technician is centrifuging a serum separator tube (SST) that contains 4 mL of blood. The centrifuge settings are 3000 RPM for 10 minutes. After centrifugation, the technician observes that the serum layer is only 1.2 mL instead of the expected 2 mL, and there appears to be slight hemolysis. What is the most likely cause of this result?
Answer: The specimen was centrifuged too soon after collection, preventing proper clot formation and gel separation
SST tubes must sit upright for 30-60 minutes after collection to allow complete clot formation before centrifugation. Centrifuging too early prevents proper clot retraction, resulting in reduced serum yield and potential hemolysis from incomplete clotting. Option A is incorrect because 3000 RPM is appropriate for SST tubes. Option C is incorrect because an unbalanced rotor would affect all tubes equally and cause vibration. Option D is incorrect because temperature primarily affects clotting time, not gel function.
- A centrifuge's daily quality control log shows that yesterday's brake setting was accidentally left on 'fast' instead of the standard 'medium' setting. All specimens processed showed normal separation appearance, but some chemistry results from those specimens are flagging as slightly elevated compared to expected ranges. What is the most likely explanation for these discrepant results?
Answer: Fast braking caused mechanical hemolysis due to rapid deceleration forces affecting red blood cell membranes
Fast brake settings can cause mechanical hemolysis due to rapid deceleration forces that stress red blood cell membranes, releasing intracellular contents (K+, LDH, AST) into serum and causing elevated chemistry results. The separation may appear normal visually but still contain hemolyzed components. Option B is incorrect because brake settings don't significantly affect temperature. Option C is incorrect because gel barriers are designed to withstand normal centrifugal forces. Option D is incorrect because fast braking typically doesn't cause visible mixing if separation was complete.
- After centrifuging a batch of specimens, a technician notices that one tube has developed a crack in the plastic. The tube contains serum that appears properly separated, but a small amount of specimen has leaked into the centrifuge bucket. What is the most appropriate immediate action sequence?
Answer: Remove the tube carefully, assess serum volume adequacy, transfer to new tube if sufficient, and decontaminate equipment
The priority is safe specimen recovery while maintaining testing capability. The technician should carefully remove the cracked tube, assess if adequate serum volume remains for testing, transfer to a new properly labeled tube if volume is sufficient, and decontaminate the centrifuge equipment according to protocol. Option A doesn't address the compromised tube adequately. Option B unnecessarily wastes a potentially usable specimen. Option D is premature - new collection should only be requested if the specimen volume is insufficient for required testing.
