NSG 550 Exam 2 Diagnostic Reasoning
(2026/2027) PDF | Nursing | Wilkes University
1. A 45-year-old male presents with acute-onset chest
pain. Which initial step in diagnostic reasoning is most
critical?
A) Order a chest X-ray
B) Generate a differential diagnosis
C) Prescribe nitroglycerin
D) Obtain a detailed social history
Correct Answer: B
Rationale: Generating a differential diagnosis guides
focused history, physical exam, and testing. Ordering
tests without a hypothesis leads to inefficiency and error.
2. A patient reports fatigue. Which probability-driven
question best refines your differential?
A) “Do you have fevers?”
B) “Has this affected your work?”
C) “What makes the fatigue worse?”
1
,D) “Rate your fatigue 1-10.”
Correct Answer: C
Rationale: Aggravating factors help distinguish cardiac
(exertional), sleep apnea (morning), or depression (worse
early day).
3. Bayesian reasoning in diagnostic testing refers to:
A) Sensitivity of a test
B) Specificity of a test
C) Incorporating pretest probability to interpret posttest
probability
D) The likelihood ratio of a negative test
Correct Answer: C
Rationale: Bayes’ theorem states that posttest probability
depends on pretest probability and test characteristics.
This prevents overinterpreting positive tests in low-risk
patients.
4. A 60-year-old with dyspnea has a pretest probability
of pulmonary embolism (PE) of 40%. D-dimer sensitivity is
2
,95%, specificity 50%. What is the most appropriate next
step?
A) Order D-dimer
B) Order CT pulmonary angiogram
C) Order chest X-ray
D) Order ventilation-perfusion scan
Correct Answer: B
Rationale: With moderate/high pretest probability
(≥40%), D-dimer has low specificity and will likely be
falsely positive. CT angiography is the appropriate
diagnostic test.
5. Which heuristic is defined as “judging the probability
of an event by how easily examples come to mind”?
A) Anchoring heuristic
B) Availability heuristic
C) Representativeness heuristic
D) Confirmation bias
Correct Answer: B
3
, Rationale: Availability heuristic leads clinicians to
overestimate common or memorable diagnoses (e.g., PE
after a high-profile case) and underestimate rare ones.
6. A 30-year-old with headache and no focal deficits has
a pretest probability of meningitis of 1%. Lumbar
puncture sensitivity is 99%, specificity 99%. A positive LP
means probability of meningitis is approximately:
A) 1%
B) 50%
C) 75%
D) 99%
Correct Answer: B
Rationale: With very low pretest probability (1%), even a
nearly perfect test yields a posttest probability around
50% due to false positives. This illustrates Bayesian
reasoning.
7. A clinician focuses on the first piece of information
received (e.g., “patient has COPD”) and fails to adjust for
4
(2026/2027) PDF | Nursing | Wilkes University
1. A 45-year-old male presents with acute-onset chest
pain. Which initial step in diagnostic reasoning is most
critical?
A) Order a chest X-ray
B) Generate a differential diagnosis
C) Prescribe nitroglycerin
D) Obtain a detailed social history
Correct Answer: B
Rationale: Generating a differential diagnosis guides
focused history, physical exam, and testing. Ordering
tests without a hypothesis leads to inefficiency and error.
2. A patient reports fatigue. Which probability-driven
question best refines your differential?
A) “Do you have fevers?”
B) “Has this affected your work?”
C) “What makes the fatigue worse?”
1
,D) “Rate your fatigue 1-10.”
Correct Answer: C
Rationale: Aggravating factors help distinguish cardiac
(exertional), sleep apnea (morning), or depression (worse
early day).
3. Bayesian reasoning in diagnostic testing refers to:
A) Sensitivity of a test
B) Specificity of a test
C) Incorporating pretest probability to interpret posttest
probability
D) The likelihood ratio of a negative test
Correct Answer: C
Rationale: Bayes’ theorem states that posttest probability
depends on pretest probability and test characteristics.
This prevents overinterpreting positive tests in low-risk
patients.
4. A 60-year-old with dyspnea has a pretest probability
of pulmonary embolism (PE) of 40%. D-dimer sensitivity is
2
,95%, specificity 50%. What is the most appropriate next
step?
A) Order D-dimer
B) Order CT pulmonary angiogram
C) Order chest X-ray
D) Order ventilation-perfusion scan
Correct Answer: B
Rationale: With moderate/high pretest probability
(≥40%), D-dimer has low specificity and will likely be
falsely positive. CT angiography is the appropriate
diagnostic test.
5. Which heuristic is defined as “judging the probability
of an event by how easily examples come to mind”?
A) Anchoring heuristic
B) Availability heuristic
C) Representativeness heuristic
D) Confirmation bias
Correct Answer: B
3
, Rationale: Availability heuristic leads clinicians to
overestimate common or memorable diagnoses (e.g., PE
after a high-profile case) and underestimate rare ones.
6. A 30-year-old with headache and no focal deficits has
a pretest probability of meningitis of 1%. Lumbar
puncture sensitivity is 99%, specificity 99%. A positive LP
means probability of meningitis is approximately:
A) 1%
B) 50%
C) 75%
D) 99%
Correct Answer: B
Rationale: With very low pretest probability (1%), even a
nearly perfect test yields a posttest probability around
50% due to false positives. This illustrates Bayesian
reasoning.
7. A clinician focuses on the first piece of information
received (e.g., “patient has COPD”) and fails to adjust for
4
