OSCE Clinical Reasoning 4 — Questions and Answers
Question 1: A 72-year-old woman with osteoporosis falls and complains of hip pain. She cannot bear weight, and her left leg appears shortened and externally rotated. What is the most likely diagnosis?
- Hip dislocation
- Femoral neck fracture (Correct answer)
- Greater trochanter fracture
- Acetabular fracture
Correct answer: Femoral neck fracture
Shortened, externally rotated leg after a fall in an elderly osteoporotic woman is the classic presentation of a femoral neck fracture.
Question 2: Which of the following best defines 'premature closure' as a diagnostic error?
- Ordering too few tests
- Accepting the first plausible diagnosis without fully excluding alternatives (Correct answer)
- Failing to document the working diagnosis
- Discharging a patient too early
Correct answer: Accepting the first plausible diagnosis without fully excluding alternatives
Premature closure is the failure to consider other diagnoses once a seemingly adequate explanation is found, and is one of the most common cognitive errors.
Question 3: A 28-year-old woman presents with pleuritic chest pain, dyspnea, and a swollen right calf after a long-haul flight. Wells score is calculated as high probability. What is the most appropriate next step?
- Order chest X-ray only
- Start anticoagulation and order CT pulmonary angiography (Correct answer)
- Order D-dimer and wait for result
- Discharge with NSAIDs
Correct answer: Start anticoagulation and order CT pulmonary angiography
A high Wells score for PE warrants immediate anticoagulation and confirmatory CT-PA, not a D-dimer (which is only useful in low pretest probability).
Question 4: A 60-year-old male with a history of alcohol use disorder presents with confusion, ataxia, and ophthalmoplegia. What is the immediate treatment?
- Normal saline bolus
- IV thiamine (Vitamin B1) (Correct answer)
- Glucose infusion
- Naloxone
Correct answer: IV thiamine (Vitamin B1)
The triad of confusion, ataxia, and ophthalmoplegia is Wernicke's encephalopathy, and IV thiamine must be given immediately — before any glucose.
Question 5: In clinical reasoning, what is meant by 'diagnostic momentum'?
- The speed at which a diagnosis is reached
- The tendency for a diagnosis made by one clinician to be accepted and perpetuated by subsequent clinicians without reassessment (Correct answer)
- Using rapid assessment tools in the emergency department
- Accelerating test ordering to reach a diagnosis faster
Correct answer: The tendency for a diagnosis made by one clinician to be accepted and perpetuated by subsequent clinicians without reassessment
Diagnostic momentum occurs when a label applied early in care propagates through the system unchallenged, even if incorrect.
Question 6: A patient presents with productive cough, fever, and right lower lobe crackles. CXR shows a lobar consolidation. Sputum gram stain shows gram-positive diplococci. What is the most likely pathogen?
- Haemophilus influenzae
- Streptococcus pneumoniae (Correct answer)
- Mycoplasma pneumoniae
- Klebsiella pneumoniae
Correct answer: Streptococcus pneumoniae
Gram-positive diplococci causing lobar pneumonia is the classic presentation of Streptococcus pneumoniae, the most common cause of community-acquired pneumonia.
Question 7: A 50-year-old woman presents with polydipsia, polyuria, and fatigue. Random blood glucose is 14 mmol/L (252 mg/dL). What additional information is most critical to determine management urgency?
- Family history of diabetes
- Presence of ketonuria or ketonemia (Correct answer)
- BMI and waist circumference
- HbA1c level
Correct answer: Presence of ketonuria or ketonemia
Detecting ketones distinguishes diabetic ketoacidosis from hyperosmolar hyperglycemic state or newly diagnosed T2DM, which have very different urgency and management.
OSCE Clinical Reasoning 4
A 72-year-old woman with osteoporosis falls and complains of hip pain.
She cannot bear weight, and her left leg appears shortened and externally rotated.
What is the most likely diagnosis?