NSG 550 Exam 1 Diagnostic Reasoning Wilkes –
(2026/2027) Actual Questions, Verified Answers with
Rationales (WU) | Guarantee Pass
SECTION 1: DIAGNOSTIC TESTING FUNDAMENTALS
1. What does sensitivity measure in diagnostic testing?
A) The ability to correctly identify patients without disease
B) The ability to correctly identify patients with disease
C) The proportion of true negatives among those without disease
D) The probability that a positive test is a true positive
Answer: B
Rationale: Sensitivity = True Positives / (True Positives + False Negatives). It
measures how well a test detects disease when the disease is truly present. A
highly sensitive test has few false negatives and is useful for ruling out disease
(SnNOut - negative result rules out) .
2. What does specificity measure?
A) Patients who have the disease
B) Patients who do not have the disease
C) The likelihood that a positive test is a true positive
D) The likelihood that a negative test is a true negative
Answer: B
Rationale: Specificity = True Negatives / (True Negatives + False Positives). A
highly specific test has few false positives and is ideal for confirming a suspected
diagnosis (SpPIn - positive result rules in) .
3. A highly specific test is most useful when the goal is to:
A) Rule out disease
B) Screen asymptomatic patients
,C) Confirm a suspected diagnosis
D) Assess disease prevalence
Answer: C
Rationale: Highly specific tests have few false positives, making them ideal for
confirming disease. Screening tests should be highly sensitive to avoid missing
cases; confirmatory tests should be highly specific to avoid over-diagnosis .
4. A new rapid test for urinary tract infection produces the same result each
time when run on the same urine sample, but many infected patients test
negative. This test is:
A) Highly sensitive but not specific
B) Precise but not accurate
C) Accurate but not precise
D) Both sensitive and specific
Answer: B
Rationale: Reproducible identical results on repeated measurements describe
high precision. However, many infected patients test negative—these are false
negatives, indicating poor sensitivity and low accuracy (proportion of all correct
results) .
5. Which concept best describes the probability that a test correctly identifies
patients with a disease?
A) Specificity
B) Sensitivity
C) Positive predictive value
D) Negative predictive value
Answer: B
Rationale: Sensitivity measures how well a test detects disease when the disease
is truly present. Positive predictive value is the probability that a positive test truly
indicates disease .
,6. A patient with suspected pulmonary embolism has a low pretest probability.
A negative D-dimer is most helpful for:
A) Confirming PE
B) Ruling out PE
C) Diagnosing COPD
D) Indicating need for CT angiogram
Answer: B
Rationale: D-dimer has high sensitivity but low specificity. In low-risk patients, a
negative D-dimer effectively rules out PE (SnNOut). In high-risk patients, a
negative D-dimer may not be sufficient, and imaging should be pursued .
7. According to Bayes' theorem, which factor most significantly influences post-
test probability?
A) Sensitivity of the assay
B) Specificity of the assay
C) Pre-test probability of the condition
D) Likelihood ratio of a positive test
Answer: C
Rationale: Bayes' theorem states that post-test probability depends on both pre-
test probability and the likelihood ratio. However, in low-risk patients, a low pre-
test probability dramatically reduces the positive predictive value even with a
high likelihood ratio. Pre-test probability is the dominant factor .
8. A 55-year-old woman is encouraged to have a screening colonoscopy. This is
an example of:
A) Primary prevention
B) Secondary prevention
C) Tertiary prevention
D) Health promotion
, Answer: B
Rationale: Secondary prevention detects disease early when it is more treatable.
Colonoscopy can identify and remove precancerous polyps, preventing cancer
development. Primary prevention prevents disease before it occurs; tertiary
prevention reduces disability from established disease .
9. Which is an example of primary prevention?
A) Annual mammography
B) Blood pressure screening
C) Immunization against influenza
D) Cardiac rehabilitation after MI
Answer: C
Rationale: Primary prevention aims to prevent disease before it occurs.
Immunizations, lifestyle counseling, and smoking cessation are primary
prevention. Screening is secondary prevention; rehabilitation is tertiary
prevention .
10. Tertiary prevention focuses on:
A) Preventing disease before it occurs
B) Early detection through screening
C) Reducing disability and complications from established disease
D) Promoting healthy lifestyles
Answer: C
Rationale: Tertiary prevention aims to improve quality of life and prevent further
deterioration. Examples include rehabilitation, chronic disease management, and
support groups .
11. The NP orders a DEXA scan for a 65-year-old woman. This test is used to
evaluate:
(2026/2027) Actual Questions, Verified Answers with
Rationales (WU) | Guarantee Pass
SECTION 1: DIAGNOSTIC TESTING FUNDAMENTALS
1. What does sensitivity measure in diagnostic testing?
A) The ability to correctly identify patients without disease
B) The ability to correctly identify patients with disease
C) The proportion of true negatives among those without disease
D) The probability that a positive test is a true positive
Answer: B
Rationale: Sensitivity = True Positives / (True Positives + False Negatives). It
measures how well a test detects disease when the disease is truly present. A
highly sensitive test has few false negatives and is useful for ruling out disease
(SnNOut - negative result rules out) .
2. What does specificity measure?
A) Patients who have the disease
B) Patients who do not have the disease
C) The likelihood that a positive test is a true positive
D) The likelihood that a negative test is a true negative
Answer: B
Rationale: Specificity = True Negatives / (True Negatives + False Positives). A
highly specific test has few false positives and is ideal for confirming a suspected
diagnosis (SpPIn - positive result rules in) .
3. A highly specific test is most useful when the goal is to:
A) Rule out disease
B) Screen asymptomatic patients
,C) Confirm a suspected diagnosis
D) Assess disease prevalence
Answer: C
Rationale: Highly specific tests have few false positives, making them ideal for
confirming disease. Screening tests should be highly sensitive to avoid missing
cases; confirmatory tests should be highly specific to avoid over-diagnosis .
4. A new rapid test for urinary tract infection produces the same result each
time when run on the same urine sample, but many infected patients test
negative. This test is:
A) Highly sensitive but not specific
B) Precise but not accurate
C) Accurate but not precise
D) Both sensitive and specific
Answer: B
Rationale: Reproducible identical results on repeated measurements describe
high precision. However, many infected patients test negative—these are false
negatives, indicating poor sensitivity and low accuracy (proportion of all correct
results) .
5. Which concept best describes the probability that a test correctly identifies
patients with a disease?
A) Specificity
B) Sensitivity
C) Positive predictive value
D) Negative predictive value
Answer: B
Rationale: Sensitivity measures how well a test detects disease when the disease
is truly present. Positive predictive value is the probability that a positive test truly
indicates disease .
,6. A patient with suspected pulmonary embolism has a low pretest probability.
A negative D-dimer is most helpful for:
A) Confirming PE
B) Ruling out PE
C) Diagnosing COPD
D) Indicating need for CT angiogram
Answer: B
Rationale: D-dimer has high sensitivity but low specificity. In low-risk patients, a
negative D-dimer effectively rules out PE (SnNOut). In high-risk patients, a
negative D-dimer may not be sufficient, and imaging should be pursued .
7. According to Bayes' theorem, which factor most significantly influences post-
test probability?
A) Sensitivity of the assay
B) Specificity of the assay
C) Pre-test probability of the condition
D) Likelihood ratio of a positive test
Answer: C
Rationale: Bayes' theorem states that post-test probability depends on both pre-
test probability and the likelihood ratio. However, in low-risk patients, a low pre-
test probability dramatically reduces the positive predictive value even with a
high likelihood ratio. Pre-test probability is the dominant factor .
8. A 55-year-old woman is encouraged to have a screening colonoscopy. This is
an example of:
A) Primary prevention
B) Secondary prevention
C) Tertiary prevention
D) Health promotion
, Answer: B
Rationale: Secondary prevention detects disease early when it is more treatable.
Colonoscopy can identify and remove precancerous polyps, preventing cancer
development. Primary prevention prevents disease before it occurs; tertiary
prevention reduces disability from established disease .
9. Which is an example of primary prevention?
A) Annual mammography
B) Blood pressure screening
C) Immunization against influenza
D) Cardiac rehabilitation after MI
Answer: C
Rationale: Primary prevention aims to prevent disease before it occurs.
Immunizations, lifestyle counseling, and smoking cessation are primary
prevention. Screening is secondary prevention; rehabilitation is tertiary
prevention .
10. Tertiary prevention focuses on:
A) Preventing disease before it occurs
B) Early detection through screening
C) Reducing disability and complications from established disease
D) Promoting healthy lifestyles
Answer: C
Rationale: Tertiary prevention aims to improve quality of life and prevent further
deterioration. Examples include rehabilitation, chronic disease management, and
support groups .
11. The NP orders a DEXA scan for a 65-year-old woman. This test is used to
evaluate:
