FISCHBACH'S A MANUAL OF
LABORATORY AND DIAGNOSTIC TESTS.
11TH EDITION
• AUTHOR(S)FRANCES FISCHBACH;
MARGARET FISCHBACH; KATE STOUT
TESTBANKS
1⃣
Reference
Ch. 1 — Diagnostic Testing
Stem
A nurse obtains a venous blood sample for a chemistry panel
but notices the patient ate a snack 30 minutes earlier. The lab
notes “nonfasting” on the requisition and reports mild
postprandial glucose elevation. Which nursing action is most
appropriate?
A. Accept the reported result and document the nonfasting
status in the chart.
B. Request the lab to cancel the test and redraw immediately
,without fasting.
C. Explain to the provider that results may be falsely elevated
and recommend repeat fasting testing.
D. Administer insulin to correct the elevated glucose prior to
repeating the test.
Correct answer
C
Rationale — Correct (3–4 sentences)
A nonfasting state can cause transient elevations in glucose and
some lipid measurements; clinical decisions should consider
that preanalytic factor. The nurse should inform the provider
that the sample was nonfasting and recommend repeating the
test under fasting conditions for accurate interpretation. This
preserves diagnostic accuracy and patient safety.
Rationale — Incorrect
A. Documenting nonfasting is necessary but passive — provider
notification and repeat testing may be required.
B. Immediate redraw without fasting will not correct
postprandial effects; fasting repeat is needed.
D. Administering insulin based solely on a nonfasting lab
without clinical assessment is inappropriate and unsafe.
Teaching point
Document preanalytic factors; repeat tests under correct
conditions when needed.
,Citation
Fischbach, F., Fischbach, M., & Stout, K. (2024). A Manual of
Laboratory and Diagnostic Tests (11th ed.). Ch. 1.
2️⃣
Reference
Ch. 1 — Diagnostic Testing
Stem
A patient in the ED has an arterial blood gas (ABG) drawn. The
sample is noted to be exposed to air and appears frothy. The lab
reports a pH of 7.30 and PaO₂ 220 mm Hg. Which interpretation
is most appropriate by the nurse?
A. Accept results—patient has severe hypoxemia and acidosis.
B. Recognize sample contamination by air can falsely raise PaO₂;
correlate clinically and consider repeat ABG.
C. Treat for hyperoxia because PaO₂ >200 mm Hg is life-
threatening.
D. Document results and no further action since ABGs are
definitive.
Correct answer
B
Rationale — Correct (3–4 sentences)
Air exposure of arterial samples introduces oxygen, producing
artifactual PaO₂ elevation and potentially altering pH. The nurse
should suspect preanalytic error, correlate with pulse oximetry
, and clinical status, and request a repeat properly handled ABG.
This prevents misdiagnosis and inappropriate therapy.
Rationale — Incorrect
A. The high PaO₂ is inconsistent with severe hypoxemia;
accepting artifact risks error.
C. PaO₂ artifact from air does not indicate life-threatening
hyperoxia requiring treatment.
D. ABGs can be invalidated by preanalytic errors; blind
acceptance is unsafe.
Teaching point
Watch for preanalytic errors (air exposure) that invalidate ABG
results.
Citation
Fischbach, F., Fischbach, M., & Stout, K. (2024). A Manual of
Laboratory and Diagnostic Tests (11th ed.). Ch. 1.
3⃣
Reference
Ch. 1 — Diagnostic Testing
Stem
A nurse preparing a patient for a CT scan with iodinated
contrast learns the patient takes metformin. The patient’s
serum creatinine is pending. What is the best immediate
nursing action?
LABORATORY AND DIAGNOSTIC TESTS.
11TH EDITION
• AUTHOR(S)FRANCES FISCHBACH;
MARGARET FISCHBACH; KATE STOUT
TESTBANKS
1⃣
Reference
Ch. 1 — Diagnostic Testing
Stem
A nurse obtains a venous blood sample for a chemistry panel
but notices the patient ate a snack 30 minutes earlier. The lab
notes “nonfasting” on the requisition and reports mild
postprandial glucose elevation. Which nursing action is most
appropriate?
A. Accept the reported result and document the nonfasting
status in the chart.
B. Request the lab to cancel the test and redraw immediately
,without fasting.
C. Explain to the provider that results may be falsely elevated
and recommend repeat fasting testing.
D. Administer insulin to correct the elevated glucose prior to
repeating the test.
Correct answer
C
Rationale — Correct (3–4 sentences)
A nonfasting state can cause transient elevations in glucose and
some lipid measurements; clinical decisions should consider
that preanalytic factor. The nurse should inform the provider
that the sample was nonfasting and recommend repeating the
test under fasting conditions for accurate interpretation. This
preserves diagnostic accuracy and patient safety.
Rationale — Incorrect
A. Documenting nonfasting is necessary but passive — provider
notification and repeat testing may be required.
B. Immediate redraw without fasting will not correct
postprandial effects; fasting repeat is needed.
D. Administering insulin based solely on a nonfasting lab
without clinical assessment is inappropriate and unsafe.
Teaching point
Document preanalytic factors; repeat tests under correct
conditions when needed.
,Citation
Fischbach, F., Fischbach, M., & Stout, K. (2024). A Manual of
Laboratory and Diagnostic Tests (11th ed.). Ch. 1.
2️⃣
Reference
Ch. 1 — Diagnostic Testing
Stem
A patient in the ED has an arterial blood gas (ABG) drawn. The
sample is noted to be exposed to air and appears frothy. The lab
reports a pH of 7.30 and PaO₂ 220 mm Hg. Which interpretation
is most appropriate by the nurse?
A. Accept results—patient has severe hypoxemia and acidosis.
B. Recognize sample contamination by air can falsely raise PaO₂;
correlate clinically and consider repeat ABG.
C. Treat for hyperoxia because PaO₂ >200 mm Hg is life-
threatening.
D. Document results and no further action since ABGs are
definitive.
Correct answer
B
Rationale — Correct (3–4 sentences)
Air exposure of arterial samples introduces oxygen, producing
artifactual PaO₂ elevation and potentially altering pH. The nurse
should suspect preanalytic error, correlate with pulse oximetry
, and clinical status, and request a repeat properly handled ABG.
This prevents misdiagnosis and inappropriate therapy.
Rationale — Incorrect
A. The high PaO₂ is inconsistent with severe hypoxemia;
accepting artifact risks error.
C. PaO₂ artifact from air does not indicate life-threatening
hyperoxia requiring treatment.
D. ABGs can be invalidated by preanalytic errors; blind
acceptance is unsafe.
Teaching point
Watch for preanalytic errors (air exposure) that invalidate ABG
results.
Citation
Fischbach, F., Fischbach, M., & Stout, K. (2024). A Manual of
Laboratory and Diagnostic Tests (11th ed.). Ch. 1.
3⃣
Reference
Ch. 1 — Diagnostic Testing
Stem
A nurse preparing a patient for a CT scan with iodinated
contrast learns the patient takes metformin. The patient’s
serum creatinine is pending. What is the best immediate
nursing action?
