CLINICAL LABORATORY SCIENCE
9TH EDITION
• AUTHOR(S)MARY LOUISE
TURGEON
TEST BANK
1
Reference: Ch. 1 — Basic Laboratory Techniques —
Fundamentals of the Clinical Laboratory
Stem: A phlebotomist brings a labeled lavender-top tube (EDTA
whole blood) from the emergency department to the central
laboratory. The specimen has a 30-minute delay from
collection, is warm to the touch, and shows slight clotting
visible near the stopper. The lab's hematology analyzer (5-part
differential) returns an unexpectedly low platelet count and an
RBC agglutination flag. What is the best immediate laboratory
action?
,A. Accept the sample and run CBC; report results with a
hemolysis comment.
B. Reject the specimen for clotting; request a new properly
mixed EDTA tube.
C. Spin and re-run platelet count on the plasma to confirm
thrombocytopenia.
D. Run a manual smear and perform saline replacement to
resolve agglutination; report adjusted platelet estimate.
Correct answer: B
Rationale — Correct: The visible clot indicates inadequate
mixing or delayed processing causing specimen integrity loss;
clotted EDTA samples produce spurious platelet and RBC count
errors. Best practice is to reject and request a new properly
collected, inverted EDTA tube to ensure accurate hematology
results. This aligns with pre-analytical quality control and
patient-safety standards.
Rationale — Incorrect A: Accepting and reporting would risk
false results and potential clinical harm; hemolysis comment
doesn't address clot.
Rationale — Incorrect C: Using plasma for platelet estimates
after clotting is invalid because clotting consumes platelets;
results will be unreliable.
Rationale — Incorrect D: Manual smear may reveal
agglutination but cannot correct a clotted sample; saline
replacement on clotted EDTA is unreliable.
,Teaching point: Visible clots in EDTA = reject specimen;
recollect with proper mixing immediately.
Citation: Turgeon, M. L. (9th ed.). Clinical Laboratory Science.
Ch. 1.
2
Reference: Ch. 1 — Basic Laboratory Techniques —
Fundamentals of the Clinical Laboratory
Stem: A small outpatient clinic performs a CLIA-waived rapid
influenza immunoassay using nasal swabs. A nurse unfamiliar
with the manufacturer's steps inverts the test cassette and
reads the result after 2 minutes (manufacturer's window: 10–15
minutes). The result is negative, but the clinician doubts it.
Which laboratory quality/ regulatory concern is most
appropriate to cite?
A. The result is a false positive due to early reading; report and
repeat.
B. The test was performed under waived complexity rules so
timing requirements are not mandatory.
C. The specimen processing violated the manufacturer's
instructions; the result is invalid and should be repeated per
protocol.
D. Because it's waived testing, the clinic can interpret results at
clinician discretion without repeating.
Correct answer: C
, Rationale — Correct: Waived tests still require following
manufacturer instructions; reading outside specified time
invalidates the result. The proper QA action is to repeat the test
using correct procedure and document the procedural
deviation. Regulatory compliance requires adherence to the IFU
(instructions for use).
Rationale — Incorrect A: Early reading more commonly causes
false negatives, not false positives; the key issue is invalid
timing.
Rationale — Incorrect B: Waived status reduces regulatory
burden but does not remove the need to follow manufacturer
instructions.
Rationale — Incorrect D: Clinical discretion cannot override
invalid testing practice; results must be repeated and
documented.
Teaching point: Even waived tests require strict adherence to
manufacturer IFU; deviations invalidate results.
Citation: Turgeon, M. L. (9th ed.). Clinical Laboratory Science.
Ch. 1.
3
Reference: Ch. 1 — Basic Laboratory Techniques —
Fundamentals of the Clinical Laboratory
Stem: During a proficiency testing (PT) event, the microbiology
section reports a discrepant organism identification compared
9TH EDITION
• AUTHOR(S)MARY LOUISE
TURGEON
TEST BANK
1
Reference: Ch. 1 — Basic Laboratory Techniques —
Fundamentals of the Clinical Laboratory
Stem: A phlebotomist brings a labeled lavender-top tube (EDTA
whole blood) from the emergency department to the central
laboratory. The specimen has a 30-minute delay from
collection, is warm to the touch, and shows slight clotting
visible near the stopper. The lab's hematology analyzer (5-part
differential) returns an unexpectedly low platelet count and an
RBC agglutination flag. What is the best immediate laboratory
action?
,A. Accept the sample and run CBC; report results with a
hemolysis comment.
B. Reject the specimen for clotting; request a new properly
mixed EDTA tube.
C. Spin and re-run platelet count on the plasma to confirm
thrombocytopenia.
D. Run a manual smear and perform saline replacement to
resolve agglutination; report adjusted platelet estimate.
Correct answer: B
Rationale — Correct: The visible clot indicates inadequate
mixing or delayed processing causing specimen integrity loss;
clotted EDTA samples produce spurious platelet and RBC count
errors. Best practice is to reject and request a new properly
collected, inverted EDTA tube to ensure accurate hematology
results. This aligns with pre-analytical quality control and
patient-safety standards.
Rationale — Incorrect A: Accepting and reporting would risk
false results and potential clinical harm; hemolysis comment
doesn't address clot.
Rationale — Incorrect C: Using plasma for platelet estimates
after clotting is invalid because clotting consumes platelets;
results will be unreliable.
Rationale — Incorrect D: Manual smear may reveal
agglutination but cannot correct a clotted sample; saline
replacement on clotted EDTA is unreliable.
,Teaching point: Visible clots in EDTA = reject specimen;
recollect with proper mixing immediately.
Citation: Turgeon, M. L. (9th ed.). Clinical Laboratory Science.
Ch. 1.
2
Reference: Ch. 1 — Basic Laboratory Techniques —
Fundamentals of the Clinical Laboratory
Stem: A small outpatient clinic performs a CLIA-waived rapid
influenza immunoassay using nasal swabs. A nurse unfamiliar
with the manufacturer's steps inverts the test cassette and
reads the result after 2 minutes (manufacturer's window: 10–15
minutes). The result is negative, but the clinician doubts it.
Which laboratory quality/ regulatory concern is most
appropriate to cite?
A. The result is a false positive due to early reading; report and
repeat.
B. The test was performed under waived complexity rules so
timing requirements are not mandatory.
C. The specimen processing violated the manufacturer's
instructions; the result is invalid and should be repeated per
protocol.
D. Because it's waived testing, the clinic can interpret results at
clinician discretion without repeating.
Correct answer: C
, Rationale — Correct: Waived tests still require following
manufacturer instructions; reading outside specified time
invalidates the result. The proper QA action is to repeat the test
using correct procedure and document the procedural
deviation. Regulatory compliance requires adherence to the IFU
(instructions for use).
Rationale — Incorrect A: Early reading more commonly causes
false negatives, not false positives; the key issue is invalid
timing.
Rationale — Incorrect B: Waived status reduces regulatory
burden but does not remove the need to follow manufacturer
instructions.
Rationale — Incorrect D: Clinical discretion cannot override
invalid testing practice; results must be repeated and
documented.
Teaching point: Even waived tests require strict adherence to
manufacturer IFU; deviations invalidate results.
Citation: Turgeon, M. L. (9th ed.). Clinical Laboratory Science.
Ch. 1.
3
Reference: Ch. 1 — Basic Laboratory Techniques —
Fundamentals of the Clinical Laboratory
Stem: During a proficiency testing (PT) event, the microbiology
section reports a discrepant organism identification compared
