OSCE Clinical Reasoning 2 — Questions and Answers
Question 1: A 68-year-old man presents with sudden onset of severe tearing chest pain radiating to his back. Blood pressure is 160/90 mmHg in the right arm and 130/75 mmHg in the left arm. What is the most likely diagnosis?
- Acute MI
- Aortic dissection (Correct answer)
- Pulmonary embolism
- Esophageal rupture
Correct answer: Aortic dissection
Unequal blood pressures between arms combined with tearing back pain is the classic presentation of aortic dissection.
Question 2: During an OSCE station, a patient's history reveals fatigue, cold intolerance, constipation, and weight gain. Which single test is most appropriate to order first?
- Fasting glucose
- TSH level (Correct answer)
- Cortisol level
- CBC
Correct answer: TSH level
TSH is the single best screening test for thyroid dysfunction, which explains all four symptoms in this clinical picture.
Question 3: A 25-year-old woman presents with right lower quadrant pain, nausea, and a positive urine hCG. Her last menstrual period was 7 weeks ago. Vital signs show HR 110, BP 90/60. What is the priority action?
- Order pelvic ultrasound
- Start IV fluids and prepare for emergency management of ectopic pregnancy (Correct answer)
- Administer antiemetics
- Perform a pelvic exam
Correct answer: Start IV fluids and prepare for emergency management of ectopic pregnancy
Hemodynamic instability with a positive pregnancy test and pelvic pain indicates likely ruptured ectopic pregnancy requiring immediate resuscitation.
Question 4: Which cognitive bias occurs when a clinician anchors on the first diagnosis made and fails to consider alternatives as new information emerges?
- Availability bias
- Anchoring bias (Correct answer)
- Premature closure
- Search satisficing
Correct answer: Anchoring bias
Anchoring bias is the tendency to rely too heavily on the initial diagnosis despite subsequent contradictory information.
Question 5: A 55-year-old male smoker presents with hemoptysis, weight loss, and a new persistent cough. Chest X-ray shows a hilar mass. What is the most important next step in the diagnostic workup?
- Sputum cytology
- CT-guided biopsy of the mass
- CT chest with contrast (Correct answer)
- PET scan
Correct answer: CT chest with contrast
CT chest with contrast is the next step to characterize the mass, assess mediastinal involvement, and plan biopsy approach before tissue diagnosis.
Question 6: A patient with known COPD presents with worsening dyspnea, increased sputum, and fever. SpO2 is 88% on room air. What oxygen target is most appropriate?
- SpO2 ≥ 98%
- SpO2 88–92% (Correct answer)
- SpO2 94–96%
- SpO2 ≥ 95%
Correct answer: SpO2 88–92%
In COPD patients, targeting SpO2 88–92% avoids hypercapnia from excessive oxygen, which can blunt their hypoxic drive.
Question 7: During a clinical encounter, after completing the history you form a differential diagnosis. What is the next best reasoning step before ordering tests?
- Order all relevant investigations simultaneously
- Rank diagnoses by probability and use physical exam to discriminate (Correct answer)
- Treat empirically for the most likely diagnosis
- Refer to a specialist
Correct answer: Rank diagnoses by probability and use physical exam to discriminate
Ranking the differential and using targeted examination findings to narrow it down is the cornerstone of efficient clinical reasoning before testing.
OSCE Clinical Reasoning 2
A 68-year-old man presents with sudden onset of severe tearing chest pain radiating to his back.
Blood pressure is 160/90 mmHg in the right arm and 130/75 mmHg in the left arm.
What is the most likely diagnosis?