OSCE Diagnostic Skills 4 — Questions and Answers
Question 1: A child presents with a barking cough, stridor, and low-grade fever. The most likely diagnosis is:
- Croup (laryngotracheobronchitis) (Correct answer)
- Epiglottitis
- Bacterial tracheitis
- Foreign body aspiration
Correct answer: Croup (laryngotracheobronchitis)
Croup typically presents in young children with a characteristic barking cough, inspiratory stridor, and mild fever due to viral subglottic oedema.
Question 2: Which investigation is most useful in differentiating prerenal from intrinsic renal acute kidney injury?
- Urinary sodium concentration and fractional excretion of sodium (FENa) (Correct answer)
- Serum urea alone
- Renal ultrasound
- Urine dipstick for protein
Correct answer: Urinary sodium concentration and fractional excretion of sodium (FENa)
FENa <1% suggests prerenal AKI (tubules conserving sodium), while FENa >2% suggests intrinsic renal disease with tubular dysfunction.
Question 3: A patient has a positive Trendelenburg test on the right side. What does this indicate?
- Weakness of the right hip abductors (gluteus medius) (Correct answer)
- Weakness of the right hip adductors
- Right hip flexor weakness
- Right knee instability
Correct answer: Weakness of the right hip abductors (gluteus medius)
A positive Trendelenburg sign on the right means the pelvis drops on the left during single-leg stance on the right, indicating weak right gluteus medius.
Question 4: Which sign is used to detect a small knee effusion that would be missed by the patellar tap test?
- Bulge (stroke) test (Correct answer)
- McMurray's test
- Lachman's test
- Thessaly test
Correct answer: Bulge (stroke) test
The bulge (stroke) test detects small effusions by milking fluid across the medial compartment and observing a bulge return medially.
Question 5: In a patient presenting with acute red eye and painful loss of vision, which diagnosis requires the most urgent intervention?
- Acute angle-closure glaucoma (Correct answer)
- Conjunctivitis
- Episcleritis
- Subconjunctival haemorrhage
Correct answer: Acute angle-closure glaucoma
Acute angle-closure glaucoma causes rapid intraocular pressure elevation leading to permanent vision loss without emergency treatment.
Question 6: When performing a Glasgow Coma Scale assessment, which component has the highest maximum score?
- Verbal response (5 points)
- Eye opening (4 points)
- Motor response (6 points) (Correct answer)
- All components are equal
Correct answer: Motor response (6 points)
The motor response component of the GCS has a maximum of 6 points, making it the highest-scoring component of the 15-point scale.
Question 7: A 60-year-old presents with sudden onset severe 'thunderclap' headache. Which investigation must be performed urgently?
- Non-contrast CT head (Correct answer)
- MRI brain with gadolinium
- Lumbar puncture alone
- EEG
Correct answer: Non-contrast CT head
Non-contrast CT head is the first-line investigation for suspected subarachnoid haemorrhage and must be performed urgently to detect acute blood.
OSCE Diagnostic Skills 4
A child presents with a barking cough, stridor, and low-grade fever.
The most likely diagnosis is: