SPEX Practice Questions (2026) — Free Sample Questions with Answers

Answer: C

Decreased intestinal absorption of vitamin K: Less vitamin K would potentiate warfarin and raise the INR, the opposite of what happened.

Inhibition of vitamin K epoxide reductase: That is warfarin's own mechanism; further inhibition of VKORC1 would increase anticoagulation and the INR.

Induction of hepatic cytochrome P450 enzymes: Correct. Rifampin is a potent inducer of CYP2C9 and CYP3A4, accelerating warfarin clearance and lowering the INR; warfarin doses often must be increased substantially.

Inhibition of hepatic cytochrome P450 enzymes: CYP inhibitors (e.g., fluconazole, amiodarone, TMP-SMX) slow warfarin metabolism and raise the INR; rifampin does the reverse.

Rifampin (also carbamazepine, phenytoin, St John's wort) induces CYP enzymes and lowers warfarin effect; azoles, amiodarone and TMP-SMX inhibit them and raise the INR.

Answer: D

Bounding carotid pulses with rapid collapse: Bounding, collapsing (water-hammer) pulses are characteristic of chronic aortic regurgitation, not stenosis.

Murmur that grows louder during Valsalva: Reduced preload from Valsalva softens the aortic stenosis murmur; a murmur that increases suggests hypertrophic obstructive cardiomyopathy.

A diastolic opening snap heard at the apex: An opening snap followed by a diastolic rumble is a sign of mitral stenosis.

Delayed and diminished carotid upstroke: Correct. Pulsus parvus et tardus reflects a fixed outflow obstruction and, with a late-peaking murmur and soft S2, indicates severe aortic stenosis.

Severe aortic stenosis: late-peaking murmur, soft or absent A2, and a slow, weak carotid upstroke; exertional syncope, angina or heart failure are indications for valve replacement.

Answer: B

Plasma D-dimer measurement: D-dimer is useful to exclude PE only when pretest probability is low or intermediate; with high probability a negative result cannot safely rule it out, so imaging is needed regardless.

CT pulmonary angiography: Correct. With high clinical probability, a stable patient and normal renal function, CT pulmonary angiography is the preferred definitive test.

Ventilation-perfusion scan: V/Q scanning is an alternative when contrast is contraindicated (renal failure, contrast allergy) or in some pregnancies; none applies here.

Transthoracic echocardiography: Echo can show right ventricular strain and is useful at the bedside in unstable patients, but it cannot confirm or exclude PE.

Assess pretest probability first: low/intermediate, start with D-dimer; high probability (or positive D-dimer), go straight to CT pulmonary angiography, using V/Q when contrast is contraindicated.

Answer: D

Portable chest radiograph to confirm the diagnosis: Tension pneumothorax is a clinical diagnosis; waiting for imaging in a hypotensive patient risks cardiac arrest.

Pericardiocentesis for presumed cardiac tamponade: Tamponade causes hypotension and distended neck veins but not unilateral absent breath sounds, hyperresonance and tracheal shift.

Rapid infusion of 2 liters of isotonic crystalloid: Fluids do not relieve the obstructive shock from rising intrathoracic pressure and only delay definitive decompression.

Immediate needle decompression of the left chest: Correct. Obstructive shock from tension pneumothorax requires immediate decompression, followed by tube thoracostomy.

Hypotension + absent breath sounds + hyperresonance + tracheal deviation = tension pneumothorax: decompress immediately, then place a chest tube; do not wait for a radiograph.

Answer: B

Report the event internally but not tell the patient: Internal reporting is necessary, but withholding the error from the patient breaches the ethical duty of honesty.

Disclose the error, apologize, explain monitoring: Correct. Physicians should promptly tell patients about errors that affect their care, explain what happened and its implications, and describe the steps taken to protect them.

Disclose the error only if a complication develops: Disclosure is owed whenever an error reaches the patient, not only after harm appears.

Refer her questions to the hospital risk manager: Risk management can support disclosure, but deflecting the patient's direct question undermines trust and the physician's duty.

Errors that reach the patient are disclosed promptly and honestly by the responsible physician, with an apology, explanation and plan; report them internally as well.

Answer: B

80%: 80% is the specificity: 80 true negatives among 100 people without disease.

82%: Correct. PPV = true positives / all positives = 90 / (90 + 20) = 90/110 ≈ 82%.

89%: 89% is the negative predictive value: 80 true negatives / (80 + 10 false negatives) = 80/90.

90%: 90% is the sensitivity: 90 true positives among 100 people with disease.

Sensitivity and specificity are read down the disease columns; PPV and NPV are read across the test-result rows (PPV = TP/(TP+FP)), and predictive values change with prevalence.