FISCHBACH'S A MANUAL OF
LABORATORY AND DIAGNOSTIC TESTS.
11TH EDITION
• AUTHOR(S)FRANCES FISCHBACH;
MARGARET FISCHBACH; KATE STOUT
TESTBANKS
1)
Reference: Ch. 1 — Diagnostic Testing
Stem: A 68-year-old patient on chronic warfarin therapy is
scheduled for an INR the morning after an evening dose. The
nurse notes the scheduled blood draw time is 10:00 a.m., but
the patient took warfarin at 20:00 last night. Which action most
appropriately ensures an interpretable INR result?
A. Proceed with the 10:00 a.m. draw; document time of last
dose.
B. Delay the draw until 24 hours after the last warfarin dose.
C. Proceed and ask the laboratory to run a dilute PT to confirm.
,D. Reschedule draw for the same time tomorrow before
medication.
Correct answer: A
Rationale — Correct: An INR reflects anticoagulation status
relative to usual dosing; documenting the time of last dose
allows proper interpretation and clinician decision-making;
immediate draw is acceptable if timing is recorded. Nurses must
document medication timing and communicate with the
provider/lab when interpreting results.
Rationale — Incorrect A: (n/a)
Rationale — Incorrect B: Delaying 24 hours would change the
clinical status and is unnecessary for routine monitoring; it may
delay important decisions.
Rationale — Incorrect C: A dilute PT is not a routine
confirmatory test for INR timing issues; communication and
documentation are primary.
Rationale — Incorrect D: Rescheduling denies current clinical
information; unnecessary unless ordered.
Teaching point: Always document last dose/time; labs interpret
INR in context of medication timing.
Citation: Fischbach, F., Fischbach, M., & Stout, K. (2024). A
Manual of Laboratory and Diagnostic Tests (11th ed.). Ch. 1.
2)
Reference: Ch. 1 — Diagnostic Testing
,Stem: A nurse collecting a urine specimen for a pregnancy test
notes the patient ate a large, iodine-rich meal an hour earlier.
Which statement best reflects the nurse’s action regarding
specimen validity?
A. Iodine intake does not affect urine hCG; proceed with
collection.
B. Ask the patient to fast 6 hours before urine pregnancy test.
C. Cancel the test; schedule a serum hCG instead.
D. Collect a first-void specimen tomorrow morning for greater
accuracy.
Correct answer: A
Rationale — Correct: Dietary iodine does not interfere with
urinary hCG immunoassays; nutrition generally does not affect
pregnancy test antigen detection. Proceed with collection per
instructions and document circumstances.
Rationale — Incorrect B: Fasting is unnecessary for urine
pregnancy testing.
Rationale — Incorrect C: Canceling or switching to serum is not
required solely due to iodine intake; serum testing may be
ordered for quantification or discordant results.
Rationale — Incorrect D: A first-void specimen can concentrate
hCG but delaying is unnecessary when immediate testing is
indicated.
Teaching point: Dietary iodine does not invalidate urine hCG
tests; follow specimen collection guidance.
, Citation: Fischbach, F., Fischbach, M., & Stout, K. (2024). A
Manual of Laboratory and Diagnostic Tests (11th ed.). Ch. 1.
3)
Reference: Ch. 1 — Diagnostic Testing
Stem: A provider orders a STAT serum potassium for a patient
with vomiting and muscle weakness. During phlebotomy the
nurse notes the sample is hemolyzed. Which is the best next
action?
A. Send the hemolyzed sample with a note; lab will interpret.
B. Recollect a nonhemolyzed specimen immediately and notify
provider.
C. Accept because hemolysis minimally affects potassium.
D. Refrigerate the hemolyzed specimen and send with the next
batch.
Correct answer: B
Rationale — Correct: Hemolysis artificially raises measured
potassium due to intracellular release; a new nonhemolyzed
specimen is required urgently and provider should be informed
for accurate management.
Rationale — Incorrect A: Sending hemolyzed sample risks
misinterpretation and possible inappropriate treatment.
Rationale — Incorrect C: Hemolysis markedly elevates
potassium; it is not minimal.
LABORATORY AND DIAGNOSTIC TESTS.
11TH EDITION
• AUTHOR(S)FRANCES FISCHBACH;
MARGARET FISCHBACH; KATE STOUT
TESTBANKS
1)
Reference: Ch. 1 — Diagnostic Testing
Stem: A 68-year-old patient on chronic warfarin therapy is
scheduled for an INR the morning after an evening dose. The
nurse notes the scheduled blood draw time is 10:00 a.m., but
the patient took warfarin at 20:00 last night. Which action most
appropriately ensures an interpretable INR result?
A. Proceed with the 10:00 a.m. draw; document time of last
dose.
B. Delay the draw until 24 hours after the last warfarin dose.
C. Proceed and ask the laboratory to run a dilute PT to confirm.
,D. Reschedule draw for the same time tomorrow before
medication.
Correct answer: A
Rationale — Correct: An INR reflects anticoagulation status
relative to usual dosing; documenting the time of last dose
allows proper interpretation and clinician decision-making;
immediate draw is acceptable if timing is recorded. Nurses must
document medication timing and communicate with the
provider/lab when interpreting results.
Rationale — Incorrect A: (n/a)
Rationale — Incorrect B: Delaying 24 hours would change the
clinical status and is unnecessary for routine monitoring; it may
delay important decisions.
Rationale — Incorrect C: A dilute PT is not a routine
confirmatory test for INR timing issues; communication and
documentation are primary.
Rationale — Incorrect D: Rescheduling denies current clinical
information; unnecessary unless ordered.
Teaching point: Always document last dose/time; labs interpret
INR in context of medication timing.
Citation: Fischbach, F., Fischbach, M., & Stout, K. (2024). A
Manual of Laboratory and Diagnostic Tests (11th ed.). Ch. 1.
2)
Reference: Ch. 1 — Diagnostic Testing
,Stem: A nurse collecting a urine specimen for a pregnancy test
notes the patient ate a large, iodine-rich meal an hour earlier.
Which statement best reflects the nurse’s action regarding
specimen validity?
A. Iodine intake does not affect urine hCG; proceed with
collection.
B. Ask the patient to fast 6 hours before urine pregnancy test.
C. Cancel the test; schedule a serum hCG instead.
D. Collect a first-void specimen tomorrow morning for greater
accuracy.
Correct answer: A
Rationale — Correct: Dietary iodine does not interfere with
urinary hCG immunoassays; nutrition generally does not affect
pregnancy test antigen detection. Proceed with collection per
instructions and document circumstances.
Rationale — Incorrect B: Fasting is unnecessary for urine
pregnancy testing.
Rationale — Incorrect C: Canceling or switching to serum is not
required solely due to iodine intake; serum testing may be
ordered for quantification or discordant results.
Rationale — Incorrect D: A first-void specimen can concentrate
hCG but delaying is unnecessary when immediate testing is
indicated.
Teaching point: Dietary iodine does not invalidate urine hCG
tests; follow specimen collection guidance.
, Citation: Fischbach, F., Fischbach, M., & Stout, K. (2024). A
Manual of Laboratory and Diagnostic Tests (11th ed.). Ch. 1.
3)
Reference: Ch. 1 — Diagnostic Testing
Stem: A provider orders a STAT serum potassium for a patient
with vomiting and muscle weakness. During phlebotomy the
nurse notes the sample is hemolyzed. Which is the best next
action?
A. Send the hemolyzed sample with a note; lab will interpret.
B. Recollect a nonhemolyzed specimen immediately and notify
provider.
C. Accept because hemolysis minimally affects potassium.
D. Refrigerate the hemolyzed specimen and send with the next
batch.
Correct answer: B
Rationale — Correct: Hemolysis artificially raises measured
potassium due to intracellular release; a new nonhemolyzed
specimen is required urgently and provider should be informed
for accurate management.
Rationale — Incorrect A: Sending hemolyzed sample risks
misinterpretation and possible inappropriate treatment.
Rationale — Incorrect C: Hemolysis markedly elevates
potassium; it is not minimal.
