NAC OSCE Clinical Reasoning & Diagnosis

Question 1

A 25-year-old woman presents with acute onset pleuritic chest pain, dyspnoea, and a history of oral contraceptive use. Which investigation should be ordered FIRST according to Canadian guidelines?

Accepted Answer

CT pulmonary angiography (CTPA) after pre-test probability assessment using the Wells PE score

Answer

Ventilation-perfusion (V/Q) scan as first line

Answer

Echocardiogram to rule out pericarditis

Answer

Arterial blood gas as the definitive test

Question 2

A 60-year-old male smoker has a 3-month history of haemoptysis, weight loss, and a right upper lobe opacity on CXR. What is the MOST appropriate next investigation?

Accepted Answer

CT chest with IV contrast followed by bronchoscopy or CT-guided biopsy

Answer

Sputum cytology as the definitive test

Answer

Repeat CXR in 6 weeks

Answer

PET scan as first-line imaging

Question 3

A 45-year-old woman presents with fatigue, weight gain, cold intolerance, and constipation. Which single test is MOST appropriate to confirm the suspected diagnosis?

Accepted Answer

TSH (thyroid-stimulating hormone)

Answer

Free T4 alone

Answer

Anti-TPO antibodies

Answer

T3 level

Question 4

In a diabetic patient presenting with fever, flank pain, and costovertebral angle tenderness, what complication must be urgently ruled out?

Accepted Answer

Emphysematous pyelonephritis requiring urgent CT and possibly nephrectomy

Answer

Simple cystitis treated with oral antibiotics

Answer

Renal calculus requiring urology referral only

Answer

Diabetic nephropathy exacerbation

Question 5

A newborn has persistent cyanosis that does not improve with supplemental oxygen. Which congenital cardiac lesion should be MOST suspected?

Accepted Answer

Transposition of the great arteries (TGA)

Answer

Tetralogy of Fallot

Answer

Ventricular septal defect

Answer

Patent ductus arteriosus

Question 6

A 30-year-old woman has episodic hypertension, headache, palpitations, and diaphoresis. Which investigation is MOST appropriate to screen for phaeochromocytoma according to Canadian Endocrine Society guidelines?

Accepted Answer

24-hour urinary metanephrines or plasma free metanephrines

Answer

24-hour urinary catecholamines alone

Answer

Clonidine suppression test as first line

Answer

MRI adrenal glands without biochemical confirmation