USMLE STEP 3 PRACTICE EXAM WITH 100
QUESTIONS, DESIGNED TO MIRROR THE
EXAM’S FOCUS ON DIAGNOSIS,
MANAGEMENT, PROGNOSIS, AND NEXT
STEPS ACROSS ALL SPECIALTIES. EACH
QUESTION HAS THE CORRECT ANSWER
IN BOLD AND THE RATIONALE IN ITALICS.
Question 1
A 55-year-old man with hypertension and diabetes presents with acute-onset
substernal chest pain radiating to the left arm, diaphoresis, and nausea. ECG
shows ST elevations in V2–V4. He is hemodynamically stable. Which is the most
appropriate initial reperfusion strategy if presentation is 90 minutes from a PCI-
capable hospital?
A) Primary PCI
B) Thrombolytics
C) CABG
D) Aspirin and clopidogrel alone
E) Nitroglycerin drip
*Rationale: For STEMI, primary PCI within 90 minutes of first medical contact is
preferred over thrombolytics. This patient is at a PCI-capable hospital, so PCI is
first-line.*
Question 2
,A 28-year-old woman at 32 weeks gestation presents with a 2-day history of
headache, blurred vision, and right upper quadrant pain. BP 165/105 mmHg.
Urine protein 4+. Platelets 90,000/μL. AST 150 U/L. What is the most appropriate
next step?
A) Delivery
B) IV labetalol
C) Magnesium sulfate
D) Oral nifedipine
E) Bed rest
Rationale: Severe preeclampsia with HELLP at 32 weeks → delivery is definitive.
Antihypertensives and magnesium are given but delivery is the priority after
stabilization.
Question 3
A 70-year-old man with a history of atrial fibrillation on apixaban presents with
sudden left arm weakness and aphasia. Last known well 2 hours ago. NIHSS 12.
Non-contrast head CT shows no hemorrhage. What is the most appropriate next
step?
A) Mechanical thrombectomy
B) IV alteplase
C) Aspirin 325 mg
D) Andexanet alfa
E) Observation
Rationale: Patient on DOAC (apixaban) within 48 hours of last dose is not eligible
for IV tPA. Mechanical thrombectomy is indicated for large vessel occlusion
regardless of anticoagulation if imaging shows salvageable tissue.
Question 4
,A 45-year-old woman presents with fatigue, arthralgias, malar rash, and oral
ulcers. ANA positive (1:640), anti-dsDNA positive, low C3/C4. Urinalysis shows
proteinuria (2+). What is the most appropriate initial therapy for lupus nephritis?
A) Mycophenolate mofetil or cyclophosphamide
B) Hydroxychloroquine alone
C) Prednisone 20 mg daily
D) Azathioprine
E) Rituximab
Rationale: Active proliferative lupus nephritis (class III/IV) requires induction with
mycophenolate mofetil or cyclophosphamide plus glucocorticoids.
Hydroxychloroquine is given but not as monotherapy.
Question 5
A 62-year-old man with COPD presents with worsening dyspnea, increased
sputum purulence, and fever. Chest X-ray shows no infiltrate. He is started on
prednisone and bronchodilators. Which finding would most strongly indicate the
need for antibiotics?
A) Purulent sputum with increased dyspnea
B) Fever alone
C) Leukocytosis
D) Positive sputum culture for Candida
E) Tachypnea
Rationale: Anthonisen criteria for COPD exacerbation: antibiotics indicated if all 3
(increased dyspnea, increased sputum volume, increased sputum purulence) or 2
including purulence.
Question 6
, A 55-year-old woman presents with acute-onset severe headache, nuchal rigidity,
and photophobia. Non-contrast head CT is normal. Lumbar puncture shows
xanthochromia. What is the most appropriate next step?
A) CT angiography
B) MRI brain
C) Repeat CT in 6 hours
D) IV antibiotics
E) Discharge with analgesics
Rationale: Xanthochromia indicates subarachnoid hemorrhage. CT negative →
next step is CTA to identify aneurysm. If negative, digital subtraction angiography.
Question 7
A 32-year-old man presents with sudden-onset scrotal pain, nausea, and vomiting.
Exam: left testis tender, elevated, absent cremasteric reflex. Doppler ultrasound
shows absent flow. What is the most appropriate next step?
A) Surgical exploration
B) Oral antibiotics
C) Manual detorsion
D) Pain control and re-exam
E) Urinalysis
Rationale: Testicular torsion is a surgical emergency. Manual detorsion can be
attempted but definitive treatment is surgery. Ultrasound delay is not appropriate
if highly suspected.
Question 8
A 45-year-old man with alcohol use disorder presents with confusion, ataxia, and
nystagmus. Which vitamin should be administered immediately?
QUESTIONS, DESIGNED TO MIRROR THE
EXAM’S FOCUS ON DIAGNOSIS,
MANAGEMENT, PROGNOSIS, AND NEXT
STEPS ACROSS ALL SPECIALTIES. EACH
QUESTION HAS THE CORRECT ANSWER
IN BOLD AND THE RATIONALE IN ITALICS.
Question 1
A 55-year-old man with hypertension and diabetes presents with acute-onset
substernal chest pain radiating to the left arm, diaphoresis, and nausea. ECG
shows ST elevations in V2–V4. He is hemodynamically stable. Which is the most
appropriate initial reperfusion strategy if presentation is 90 minutes from a PCI-
capable hospital?
A) Primary PCI
B) Thrombolytics
C) CABG
D) Aspirin and clopidogrel alone
E) Nitroglycerin drip
*Rationale: For STEMI, primary PCI within 90 minutes of first medical contact is
preferred over thrombolytics. This patient is at a PCI-capable hospital, so PCI is
first-line.*
Question 2
,A 28-year-old woman at 32 weeks gestation presents with a 2-day history of
headache, blurred vision, and right upper quadrant pain. BP 165/105 mmHg.
Urine protein 4+. Platelets 90,000/μL. AST 150 U/L. What is the most appropriate
next step?
A) Delivery
B) IV labetalol
C) Magnesium sulfate
D) Oral nifedipine
E) Bed rest
Rationale: Severe preeclampsia with HELLP at 32 weeks → delivery is definitive.
Antihypertensives and magnesium are given but delivery is the priority after
stabilization.
Question 3
A 70-year-old man with a history of atrial fibrillation on apixaban presents with
sudden left arm weakness and aphasia. Last known well 2 hours ago. NIHSS 12.
Non-contrast head CT shows no hemorrhage. What is the most appropriate next
step?
A) Mechanical thrombectomy
B) IV alteplase
C) Aspirin 325 mg
D) Andexanet alfa
E) Observation
Rationale: Patient on DOAC (apixaban) within 48 hours of last dose is not eligible
for IV tPA. Mechanical thrombectomy is indicated for large vessel occlusion
regardless of anticoagulation if imaging shows salvageable tissue.
Question 4
,A 45-year-old woman presents with fatigue, arthralgias, malar rash, and oral
ulcers. ANA positive (1:640), anti-dsDNA positive, low C3/C4. Urinalysis shows
proteinuria (2+). What is the most appropriate initial therapy for lupus nephritis?
A) Mycophenolate mofetil or cyclophosphamide
B) Hydroxychloroquine alone
C) Prednisone 20 mg daily
D) Azathioprine
E) Rituximab
Rationale: Active proliferative lupus nephritis (class III/IV) requires induction with
mycophenolate mofetil or cyclophosphamide plus glucocorticoids.
Hydroxychloroquine is given but not as monotherapy.
Question 5
A 62-year-old man with COPD presents with worsening dyspnea, increased
sputum purulence, and fever. Chest X-ray shows no infiltrate. He is started on
prednisone and bronchodilators. Which finding would most strongly indicate the
need for antibiotics?
A) Purulent sputum with increased dyspnea
B) Fever alone
C) Leukocytosis
D) Positive sputum culture for Candida
E) Tachypnea
Rationale: Anthonisen criteria for COPD exacerbation: antibiotics indicated if all 3
(increased dyspnea, increased sputum volume, increased sputum purulence) or 2
including purulence.
Question 6
, A 55-year-old woman presents with acute-onset severe headache, nuchal rigidity,
and photophobia. Non-contrast head CT is normal. Lumbar puncture shows
xanthochromia. What is the most appropriate next step?
A) CT angiography
B) MRI brain
C) Repeat CT in 6 hours
D) IV antibiotics
E) Discharge with analgesics
Rationale: Xanthochromia indicates subarachnoid hemorrhage. CT negative →
next step is CTA to identify aneurysm. If negative, digital subtraction angiography.
Question 7
A 32-year-old man presents with sudden-onset scrotal pain, nausea, and vomiting.
Exam: left testis tender, elevated, absent cremasteric reflex. Doppler ultrasound
shows absent flow. What is the most appropriate next step?
A) Surgical exploration
B) Oral antibiotics
C) Manual detorsion
D) Pain control and re-exam
E) Urinalysis
Rationale: Testicular torsion is a surgical emergency. Manual detorsion can be
attempted but definitive treatment is surgery. Ultrasound delay is not appropriate
if highly suspected.
Question 8
A 45-year-old man with alcohol use disorder presents with confusion, ataxia, and
nystagmus. Which vitamin should be administered immediately?
