Wilkes University NSG 550 Exam 2 (pdf) | 2026/2027 |
Diagnostic Reasoning Q&A | Nurse Practitioner
1. A nurse practitioner is evaluating a patient with suspected pulmonary embolism.
Which diagnostic test, when normal, is most useful for ruling out this condition?
A) D-dimer
B) Chest X-ray
C) V/Q scan
D) Arterial blood gas
Correct Answer: D-dimer
Rationale: The D-dimer test has high sensitivity and negative predictive value for pulmonary
embolism. A normal D-dimer effectively rules out PE in low-risk patients, as it reflects the
absence of active fibrin degradation. Chest X-ray, V/Q scan, and ABG lack this rule-out
capability and are used for different diagnostic purposes.-10
2. A 32-year-old man presents with early-onset emphysema and a strong family history
of lung disease. Which diagnostic test is most appropriate to identify a hereditary
cause?
A) D-dimer level
B) Alpha1-antitrypsin level and genetic testing
C) Arterial blood gases
D) V/Q scan
Correct Answer: Alpha1-antitrypsin level and genetic testing
Rationale: Alpha1-antitrypsin deficiency is associated with early-onset emphysema,
especially with a positive family history. Serum AAT level with genetic testing confirms the
diagnosis and enables appropriate counseling. D-dimer and V/Q scan evaluate
thromboembolic disease, while ABGs assess gas exchange without identifying genetic
etiology.-10
3. Which arterial blood gas parameter directly reflects the effectiveness of oxygen
therapy in a patient with respiratory failure?
A) pH
B) PCO2
C) HCO3
D) PO2
Correct Answer: PO2
,Rationale: PO2 measures the partial pressure of oxygen and reflects the force of oxygen to
diffuse across the pulmonary membrane. It directly assesses the effectiveness of
supplemental oxygen therapy. pH, PCO2, and HCO3 evaluate acid-base status rather than
oxygenation adequacy.-6
4. A 58-year-old immobilized man after hip surgery complains of sudden dyspnea and
pleuritic chest pain. A D-dimer returns within normal limits. How should this result
be interpreted?
A) PE is effectively ruled out
B) PE is confirmed
C) The result is unhelpful in inpatients
D) Myocardial infarction is indicated
Correct Answer: PE is effectively ruled out
Rationale: D-dimer has a high negative predictive value for pulmonary embolism in low-to-
moderate risk patients. A normal result makes PE unlikely and can guide discontinuation of
further workup. In high-risk or hospitalized patients, clinical judgment and imaging may still
be warranted.-10
5. Which diagnostic study is most useful for monitoring the clinical course of
sarcoidosis?
A) Carboxyhemoglobin level
B) Serum angiotensin-converting enzyme level
C) Troponin I level
D) D-dimer level
Correct Answer: Serum angiotensin-converting enzyme level
Rationale: Serum ACE levels are elevated in sarcoidosis and are used to monitor disease
activity and treatment response. Carboxyhemoglobin evaluates carbon monoxide
exposure, troponin assesses myocardial injury, and D-dimer screens for intravascular
clotting.-10
6. A 45-year-old presents with acute 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: Generate a differential diagnosis
,Rationale: Generating a differential diagnosis guides focused history, physical examination,
and diagnostic testing. Ordering tests without a working hypothesis leads to inefficiency
and diagnostic error. This structured approach ensures that high-risk conditions are
considered first.-14
7. A nurse practitioner uses a dual-process model of reasoning. Which scenario best
describes intuitive (Type 1) processing?
A) Calculating pre-test probability for PE
B) Recognizing "sick vs. not sick" within seconds
C) Listing all causes of fatigue systematically
D) Using a clinical decision rule for ankle trauma
Correct Answer: Recognizing "sick vs. not sick" within seconds
Rationale: Type 1 reasoning is rapid, subconscious, and pattern-based. Recognizing illness
severity instantly is a hallmark of intuitive processing. The other options involve deliberate,
analytical Type 2 reasoning that requires cognitive effort.-4
8. Which cognitive bias is defined as the tendency to judge probability by how easily
examples come to mind?
A) Anchoring
B) Availability
C) Confirmation bias
D) Premature closure
Correct Answer: Availability
Rationale: The availability heuristic causes clinicians to overestimate the likelihood of
recent or memorable diagnoses. Anchoring involves fixating on initial data, confirmation
bias seeks supporting evidence, and premature closure stops the diagnostic process too
early.-4
9. To avoid premature closure, a nurse practitioner should:
A) Stop ordering tests once the most likely diagnosis is found
B) Continue to consider alternative diagnoses after reaching a working diagnosis
C) Rely solely on the first impression
D) Order every possible test regardless of relevance
Correct Answer: Continue to consider alternative diagnoses after reaching a working
diagnosis
Rationale: Premature closure occurs when a clinician accepts a diagnosis before fully
verifying it. Maintaining a broad differential and reconsidering alternatives reduces
, diagnostic error. Stopping early or relying on first impressions increases the risk of missed
diagnoses.-4
10. Which statistical measure refers to a test's ability to correctly identify those without
disease?
A) Sensitivity
B) Positive predictive value
C) Specificity
D) Negative predictive value
Correct Answer: Specificity
Rationale: Specificity is the proportion of true negatives correctly identified. A highly
specific test has a low false-positive rate and is useful for ruling in a disease when positive.
Sensitivity measures true positives, while predictive values depend on disease prevalence.-
11
11. A highly sensitive screening test is primarily used for which clinical purpose?
A) Ruling in a diagnosis
B) Identifying a specific pathogen
C) Ruling out a diagnosis
D) Predicting disease severity
Correct Answer: Ruling out a diagnosis
Rationale: Highly sensitive tests have very few false negatives, so a negative result reliably
excludes the condition. This is summarized by the mnemonic "SnNout" (Sensitive test,
Negative result, rules out). Specific tests are used for ruling in disease.-11
12. The positive predictive value of a diagnostic test is most significantly influenced by
which factor?
A) Sensitivity
B) Specificity
C) Disease prevalence
D) Test cost
Correct Answer: Disease prevalence
Rationale: PPV varies directly with disease prevalence. In high-prevalence settings, a
positive result is more likely to be a true positive. In low-prevalence settings, even highly
specific tests produce more false positives, lowering PPV.-11
Diagnostic Reasoning Q&A | Nurse Practitioner
1. A nurse practitioner is evaluating a patient with suspected pulmonary embolism.
Which diagnostic test, when normal, is most useful for ruling out this condition?
A) D-dimer
B) Chest X-ray
C) V/Q scan
D) Arterial blood gas
Correct Answer: D-dimer
Rationale: The D-dimer test has high sensitivity and negative predictive value for pulmonary
embolism. A normal D-dimer effectively rules out PE in low-risk patients, as it reflects the
absence of active fibrin degradation. Chest X-ray, V/Q scan, and ABG lack this rule-out
capability and are used for different diagnostic purposes.-10
2. A 32-year-old man presents with early-onset emphysema and a strong family history
of lung disease. Which diagnostic test is most appropriate to identify a hereditary
cause?
A) D-dimer level
B) Alpha1-antitrypsin level and genetic testing
C) Arterial blood gases
D) V/Q scan
Correct Answer: Alpha1-antitrypsin level and genetic testing
Rationale: Alpha1-antitrypsin deficiency is associated with early-onset emphysema,
especially with a positive family history. Serum AAT level with genetic testing confirms the
diagnosis and enables appropriate counseling. D-dimer and V/Q scan evaluate
thromboembolic disease, while ABGs assess gas exchange without identifying genetic
etiology.-10
3. Which arterial blood gas parameter directly reflects the effectiveness of oxygen
therapy in a patient with respiratory failure?
A) pH
B) PCO2
C) HCO3
D) PO2
Correct Answer: PO2
,Rationale: PO2 measures the partial pressure of oxygen and reflects the force of oxygen to
diffuse across the pulmonary membrane. It directly assesses the effectiveness of
supplemental oxygen therapy. pH, PCO2, and HCO3 evaluate acid-base status rather than
oxygenation adequacy.-6
4. A 58-year-old immobilized man after hip surgery complains of sudden dyspnea and
pleuritic chest pain. A D-dimer returns within normal limits. How should this result
be interpreted?
A) PE is effectively ruled out
B) PE is confirmed
C) The result is unhelpful in inpatients
D) Myocardial infarction is indicated
Correct Answer: PE is effectively ruled out
Rationale: D-dimer has a high negative predictive value for pulmonary embolism in low-to-
moderate risk patients. A normal result makes PE unlikely and can guide discontinuation of
further workup. In high-risk or hospitalized patients, clinical judgment and imaging may still
be warranted.-10
5. Which diagnostic study is most useful for monitoring the clinical course of
sarcoidosis?
A) Carboxyhemoglobin level
B) Serum angiotensin-converting enzyme level
C) Troponin I level
D) D-dimer level
Correct Answer: Serum angiotensin-converting enzyme level
Rationale: Serum ACE levels are elevated in sarcoidosis and are used to monitor disease
activity and treatment response. Carboxyhemoglobin evaluates carbon monoxide
exposure, troponin assesses myocardial injury, and D-dimer screens for intravascular
clotting.-10
6. A 45-year-old presents with acute 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: Generate a differential diagnosis
,Rationale: Generating a differential diagnosis guides focused history, physical examination,
and diagnostic testing. Ordering tests without a working hypothesis leads to inefficiency
and diagnostic error. This structured approach ensures that high-risk conditions are
considered first.-14
7. A nurse practitioner uses a dual-process model of reasoning. Which scenario best
describes intuitive (Type 1) processing?
A) Calculating pre-test probability for PE
B) Recognizing "sick vs. not sick" within seconds
C) Listing all causes of fatigue systematically
D) Using a clinical decision rule for ankle trauma
Correct Answer: Recognizing "sick vs. not sick" within seconds
Rationale: Type 1 reasoning is rapid, subconscious, and pattern-based. Recognizing illness
severity instantly is a hallmark of intuitive processing. The other options involve deliberate,
analytical Type 2 reasoning that requires cognitive effort.-4
8. Which cognitive bias is defined as the tendency to judge probability by how easily
examples come to mind?
A) Anchoring
B) Availability
C) Confirmation bias
D) Premature closure
Correct Answer: Availability
Rationale: The availability heuristic causes clinicians to overestimate the likelihood of
recent or memorable diagnoses. Anchoring involves fixating on initial data, confirmation
bias seeks supporting evidence, and premature closure stops the diagnostic process too
early.-4
9. To avoid premature closure, a nurse practitioner should:
A) Stop ordering tests once the most likely diagnosis is found
B) Continue to consider alternative diagnoses after reaching a working diagnosis
C) Rely solely on the first impression
D) Order every possible test regardless of relevance
Correct Answer: Continue to consider alternative diagnoses after reaching a working
diagnosis
Rationale: Premature closure occurs when a clinician accepts a diagnosis before fully
verifying it. Maintaining a broad differential and reconsidering alternatives reduces
, diagnostic error. Stopping early or relying on first impressions increases the risk of missed
diagnoses.-4
10. Which statistical measure refers to a test's ability to correctly identify those without
disease?
A) Sensitivity
B) Positive predictive value
C) Specificity
D) Negative predictive value
Correct Answer: Specificity
Rationale: Specificity is the proportion of true negatives correctly identified. A highly
specific test has a low false-positive rate and is useful for ruling in a disease when positive.
Sensitivity measures true positives, while predictive values depend on disease prevalence.-
11
11. A highly sensitive screening test is primarily used for which clinical purpose?
A) Ruling in a diagnosis
B) Identifying a specific pathogen
C) Ruling out a diagnosis
D) Predicting disease severity
Correct Answer: Ruling out a diagnosis
Rationale: Highly sensitive tests have very few false negatives, so a negative result reliably
excludes the condition. This is summarized by the mnemonic "SnNout" (Sensitive test,
Negative result, rules out). Specific tests are used for ruling in disease.-11
12. The positive predictive value of a diagnostic test is most significantly influenced by
which factor?
A) Sensitivity
B) Specificity
C) Disease prevalence
D) Test cost
Correct Answer: Disease prevalence
Rationale: PPV varies directly with disease prevalence. In high-prevalence settings, a
positive result is more likely to be a true positive. In low-prevalence settings, even highly
specific tests produce more false positives, lowering PPV.-11
