ABPS Diagnostic Testing & Interpretation Flashcards

A patient's ECG shows a delta wave and shortened PR interval. Which condition does this pattern suggest?

Answer: Wolff-Parkinson-White (WPW) syndrome

WPW syndrome results from an accessory conduction pathway (Bundle of Kent) that pre-excites the ventricles, causing the characteristic delta wave and short PR interval on ECG.

Which finding on urinalysis is most specific for a urinary tract infection caused by bacteria?

Answer: Nitrites and leukocyte esterase

Nitrites (produced by gram-negative bacteria reducing nitrates) combined with leukocyte esterase (indicating pyuria) together have high specificity for bacterial UTI.

A chest X-ray shows a unilateral 'ground-glass opacity' pattern in an immunocompromised patient. Which pathogen should be highest on the differential?

Answer: Pneumocystis jirovecii (PCP)

Bilateral perihilar ground-glass opacities on CXR in an immunocompromised host (especially HIV with low CD4) are classic for Pneumocystis jirovecii pneumonia.

Which serum marker is most useful for monitoring the effectiveness of treatment in a patient with hepatocellular carcinoma?

Answer: AFP (alpha-fetoprotein)

AFP is produced by hepatocellular carcinoma cells and is used both as a diagnostic marker and to monitor treatment response and recurrence.

An ABG shows pH 7.28, PaCO2 55 mmHg, HCO3 24 mEq/L. How would you classify this acid-base disorder?

Answer: Respiratory acidosis (uncompensated)

The low pH with elevated PaCO2 and normal bicarbonate indicates acute (uncompensated) respiratory acidosis, consistent with hypoventilation.

In interpreting a screening test, which statistical measure describes the probability that a person with a negative test truly does not have the disease?

Answer: Negative predictive value

Negative predictive value (NPV) is the proportion of true negatives among all individuals who tested negative, indicating the probability of being disease-free given a negative result.