FISCHBACH'S A MANUAL OF
LABORATORY AND DIAGNOSTIC TESTS.
11TH EDITION
• AUTHOR(S)FRANCES FISCHBACH;
MARGARET FISCHBACH; KATE STOUT
TESTBANKS
Ch. 1 — Diagnostic Testing
Stem: A nurse receives a routine chemistry specimen that
appears pink-tinged after centrifugation. The lab reports
hemolysis and warns that potassium (K⁺) may be falsely
elevated. Which action is the nurse’s best next step?
A. Document the hemolyzed specimen and proceed with
treatment based on the reported K⁺ value.
B. Request a repeat venous draw with careful technique and
send a new sample.
C. Order an immediate ECG and treat for hyperkalemia since
any elevated K⁺ is clinically significant.
,D. Ask the lab to run the specimen anyway and compare trends
with prior values.
Correct answer: B
Rationales
Correct (B): Hemolysis releases intracellular K⁺, falsely raising
serum potassium. A repeat specimen collected using correct
technique (no excessive tourniquet time, proper needle size,
avoid squeezing) provides an accurate value and prevents
inappropriate treatment. Nursing implication: hold action until
a reliable result is obtained and notify provider of the repeat.
A: Incorrect — documenting only is unsafe because hemolysis
invalidates the K⁺ result; acting on it risks mismanagement.
C: Incorrect — immediate ECG/treatment is indicated only
when true hyperkalemia is confirmed or with compatible ECG
changes and symptoms; hemolyzed samples can be false
positives.
D: Incorrect — running a hemolyzed specimen may provide
misleading results; trend comparison is useful only with valid
samples.
Teaching point: Hemolyzed samples can falsely elevate
intracellular analytes — repeat the draw when in doubt.
Citation: Fischbach, F., Fischbach, M., & Stout, K. (2024). A
Manual of Laboratory and Diagnostic Tests (11th ed.). Ch. 1.
Ch. 1 — Diagnostic Testing
,Stem: A patient’s point-of-care glucose (POC) fingerstick reads
42 mg/dL and the patient is drowsy and pale. Which is the
nurse’s best immediate action?
A. Give 4 oz fruit juice orally and recheck fingerstick glucose in
15 minutes.
B. Notify the provider and wait for orders before giving
anything.
C. Reposition the patient and recheck the glucose in 30
minutes.
D. Discard the POC value and send a venous sample to the lab
for confirmatory testing before acting.
Correct answer: A
Rationales
Correct (A): A POC glucose of 42 mg/dL with altered mental
status indicates symptomatic hypoglycemia requiring
immediate treatment (oral carbohydrate if airway intact).
Nursing priority per diagnostic testing principles is to treat
hypoglycemia promptly, then recheck glucose and document
response.
B: Incorrect — waiting for provider orders delays urgent therapy
for a critically low glucose with symptoms.
C: Incorrect — delay may worsen hypoglycemia; 30 minutes is
too long before reassessment or therapy.
D: Incorrect — confirmatory venous testing is reasonable but
not before treating symptomatic hypoglycemia; POC devices are
used for immediate clinical decisions.
, Teaching point: Treat symptomatic hypoglycemia immediately;
recheck glucose 15 minutes after treatment.
Citation: Fischbach, F., Fischbach, M., & Stout, K. (2024). A
Manual of Laboratory and Diagnostic Tests (11th ed.). Ch. 1.
Ch. 1 — Diagnostic Testing
Stem: A nurse is collecting blood cultures for a febrile patient.
Which practice best reduces false-positive (contaminant)
culture results?
A. Collect one culture set from the intravenous (IV) line only.
B. Collect two sets from separate venipuncture sites after strict
skin antisepsis.
C. Draw cultures immediately after administering IV antibiotics.
D. Use a syringe and transfer technique to draw from a central
line without cleaning the hub.
Correct answer: B
Rationales
Correct (B): Two culture sets from separate venipuncture sites
with proper skin antisepsis reduce contamination and increase
diagnostic yield for bacteremia. Ch. 1 emphasizes preanalytic
technique (skin prep, timing, site selection) to ensure accurate
microbiologic testing. Nursing responsibility: follow aseptic
technique and document collection times.
A: Incorrect — drawing only from the IV line increases
contamination risk and may miss intermittent bacteremia.
LABORATORY AND DIAGNOSTIC TESTS.
11TH EDITION
• AUTHOR(S)FRANCES FISCHBACH;
MARGARET FISCHBACH; KATE STOUT
TESTBANKS
Ch. 1 — Diagnostic Testing
Stem: A nurse receives a routine chemistry specimen that
appears pink-tinged after centrifugation. The lab reports
hemolysis and warns that potassium (K⁺) may be falsely
elevated. Which action is the nurse’s best next step?
A. Document the hemolyzed specimen and proceed with
treatment based on the reported K⁺ value.
B. Request a repeat venous draw with careful technique and
send a new sample.
C. Order an immediate ECG and treat for hyperkalemia since
any elevated K⁺ is clinically significant.
,D. Ask the lab to run the specimen anyway and compare trends
with prior values.
Correct answer: B
Rationales
Correct (B): Hemolysis releases intracellular K⁺, falsely raising
serum potassium. A repeat specimen collected using correct
technique (no excessive tourniquet time, proper needle size,
avoid squeezing) provides an accurate value and prevents
inappropriate treatment. Nursing implication: hold action until
a reliable result is obtained and notify provider of the repeat.
A: Incorrect — documenting only is unsafe because hemolysis
invalidates the K⁺ result; acting on it risks mismanagement.
C: Incorrect — immediate ECG/treatment is indicated only
when true hyperkalemia is confirmed or with compatible ECG
changes and symptoms; hemolyzed samples can be false
positives.
D: Incorrect — running a hemolyzed specimen may provide
misleading results; trend comparison is useful only with valid
samples.
Teaching point: Hemolyzed samples can falsely elevate
intracellular analytes — repeat the draw when in doubt.
Citation: Fischbach, F., Fischbach, M., & Stout, K. (2024). A
Manual of Laboratory and Diagnostic Tests (11th ed.). Ch. 1.
Ch. 1 — Diagnostic Testing
,Stem: A patient’s point-of-care glucose (POC) fingerstick reads
42 mg/dL and the patient is drowsy and pale. Which is the
nurse’s best immediate action?
A. Give 4 oz fruit juice orally and recheck fingerstick glucose in
15 minutes.
B. Notify the provider and wait for orders before giving
anything.
C. Reposition the patient and recheck the glucose in 30
minutes.
D. Discard the POC value and send a venous sample to the lab
for confirmatory testing before acting.
Correct answer: A
Rationales
Correct (A): A POC glucose of 42 mg/dL with altered mental
status indicates symptomatic hypoglycemia requiring
immediate treatment (oral carbohydrate if airway intact).
Nursing priority per diagnostic testing principles is to treat
hypoglycemia promptly, then recheck glucose and document
response.
B: Incorrect — waiting for provider orders delays urgent therapy
for a critically low glucose with symptoms.
C: Incorrect — delay may worsen hypoglycemia; 30 minutes is
too long before reassessment or therapy.
D: Incorrect — confirmatory venous testing is reasonable but
not before treating symptomatic hypoglycemia; POC devices are
used for immediate clinical decisions.
, Teaching point: Treat symptomatic hypoglycemia immediately;
recheck glucose 15 minutes after treatment.
Citation: Fischbach, F., Fischbach, M., & Stout, K. (2024). A
Manual of Laboratory and Diagnostic Tests (11th ed.). Ch. 1.
Ch. 1 — Diagnostic Testing
Stem: A nurse is collecting blood cultures for a febrile patient.
Which practice best reduces false-positive (contaminant)
culture results?
A. Collect one culture set from the intravenous (IV) line only.
B. Collect two sets from separate venipuncture sites after strict
skin antisepsis.
C. Draw cultures immediately after administering IV antibiotics.
D. Use a syringe and transfer technique to draw from a central
line without cleaning the hub.
Correct answer: B
Rationales
Correct (B): Two culture sets from separate venipuncture sites
with proper skin antisepsis reduce contamination and increase
diagnostic yield for bacteremia. Ch. 1 emphasizes preanalytic
technique (skin prep, timing, site selection) to ensure accurate
microbiologic testing. Nursing responsibility: follow aseptic
technique and document collection times.
A: Incorrect — drawing only from the IV line increases
contamination risk and may miss intermittent bacteremia.
