What are the common cases and their management in the MRCP (Membership of the Royal College of Physicians) PACES (Practical Assessment of Clinical Examination Skills) exam?

Common MRCP PACES Cases and Differential Diagnoses

Overview of MRCP PACES Examination Structure

The MRCP PACES examination assesses clinical skills across five stations, with candidates rotating through different clinical scenarios that test examination technique, diagnostic reasoning, and communication skills. 1, 2 The examination evaluates competence across respiratory, cardiovascular, abdominal, neurological, and communication domains, with pass rates varying significantly based on candidate background and preparation 3.

High-Yield Cardiovascular Cases

Congenital Heart Disease Presentations

Adult congenital heart disease (ACHD) cases are frequently encountered and require systematic classification by complexity:

Simple Complexity (Class I)

• Repaired atrial septal defect (ASD) or ventricular septal defect (VSD) without residual shunt or chamber enlargement 4
• Mild isolated pulmonary stenosis 4
• Previously ligated patent ductus arteriosus 4

Moderate Complexity (Class II)

• Coarctation of the aorta - look for radio-femoral delay, upper limb hypertension, and rib notching 4
• Ebstein anomaly - presents with tricuspid regurgitation and right heart enlargement 4
• Repaired tetralogy of Fallot - examine for residual pulmonary regurgitation and right ventricular dysfunction 4
• Congenital aortic or mitral valve disease 4

Great Complexity (Class III)

• Fontan circulation - single ventricle physiology with cavopulmonary connection 4
• Transposition of great arteries (TGA) - post-arterial switch or atrial switch 4
• Cyanotic congenital heart disease (unoperated or palliated) 4

Peripheral Arterial Disease

Examine systematically for PAD by assessing pulse intensity (0=absent, 1=diminished, 2=normal, 3=bounding) at brachial, radial, ulnar, femoral, popliteal, dorsalis pedis, and posterior tibial sites. 4 Auscultate femoral arteries for bruits and inspect feet for trophic changes, ulcerations, and distal hair loss 4.

Key risk stratification:

• Age <50 years with diabetes plus one atherosclerosis risk factor 4
• Age 50-69 years with smoking history or diabetes 4
• Age ≥70 years regardless of risk factors 4

Abdominal/Hepatobiliary Cases

Jaundice Approach

When encountering jaundice in PACES, immediately classify as pre-hepatic, hepatic, or post-hepatic based on clinical features and examination findings. 5

Primary Sclerosing Cholangitis (PSC)

PSC presents with persistently elevated alkaline phosphatase and gamma-glutamyltransferase in a cholestatic pattern, often with concomitant inflammatory bowel disease (50-80% of cases). 4

Diagnostic algorithm:

1. Elevated ALP + GGT → Ultrasound to exclude dilated ducts/stones 4
2. If ultrasound normal → Check AMA/ANA for primary biliary cholangitis 4
3. If negative → MRCP as first-line imaging (sensitivity 86%, specificity 94%) 4
4. ERCP only if MRCP equivocal or contraindicated 4

Cholangiographic features to identify:

• Multifocal intrahepatic and extrahepatic bile duct strictures with "beaded" appearance 4
• Slight biliary dilatation with diverticular outpouchings 4
• "Pruned tree" appearance in chronic stages 4

Differential diagnoses with similar cholangiographic features:

• IgG4-related cholangitis - multifocal central strictures with bile duct wall thickening 4
• Ischemic cholangitis - proximal intrahepatic strictures with bile duct necrosis 4
• AIDS-related cholangitis - distal common bile duct stricture with papillitis 4

Respiratory Cases

Pulmonary Hypertension

Define pulmonary hypertension as mean PA pressure ≥25 mmHg by right heart catheterization, with pulmonary arterial hypertension requiring additional criteria of pulmonary capillary wedge pressure ≤15 mmHg and pulmonary vascular resistance ≥3 Wood units. 4

Clinical classification to memorize:

Group 1: Pulmonary Arterial Hypertension

• Idiopathic PAH 4
• Heritable (BMPR2, ALK-1 mutations) 4
• Associated with connective tissue disease, HIV, portal hypertension, congenital heart disease 4

Group 2: Left Heart Disease

• Systolic or diastolic dysfunction, valvular disease 4

Group 3: Lung Disease/Hypoxia

• COPD, interstitial lung disease, sleep-disordered breathing 4

Group 4: Chronic Thromboembolic PH

• Requires ventilation/perfusion scan for screening (sensitivity >90%, specificity >94%) 4

Examination findings:

• Loud P2, right ventricular heave, elevated JVP, peripheral edema 4
• Tricuspid regurgitation murmur, pulmonic regurgitation 4

Uncommon Respiratory Causes of Chronic Cough

When common causes are excluded, consider uncommon pulmonary disorders:

Large Airway Disorders

• Tracheobronchomalacia - dynamic airway collapse 4
• Airway stenosis/strictures 4
• Tracheobronchopathia osteoplastica 4

Key diagnostic approach: Flow-volume curves and direct bronchoscopy are more helpful than imaging for large airway disorders. 4

Parenchymal Disorders

• Lymphangioleiomyomatosis 4
• Pulmonary Langerhans cell histiocytosis 4
• Pulmonary alveolar proteinosis 4

Systemic/Multisystem Cases

Connective Tissue Diseases with Respiratory Manifestations

Connective tissue diseases frequently present with respiratory complications as major symptoms:

• Rheumatoid arthritis, systemic lupus erythematosus, scleroderma, Sjögren syndrome 4
• Mixed connective tissue disease, relapsing polychondritis 4

Vasculitides

• Wegener granulomatosis (GPA) 4
• Giant cell arteritis (temporal arteritis) 4
• Relapsing polychondritis 4

Examination Technique Pearls

Physical Examination Documentation

Record pulse examination numerically: 0=absent, 1=diminished, 2=normal, 3=bounding at all major sites. 4

For abdominal examination:

• Palpate for aortic pulsation and maximal diameter 4
• Auscultate abdomen and flanks for bruits 4
• Remove shoes and socks to inspect feet for trophic changes, ulcerations, and color/temperature abnormalities 4

NYHA Functional Classification

Memorize precise NYHA definitions for cardiovascular limitation:

• Class I: No limitation, ordinary activity causes no symptoms 4
• Class II: Slight limitation, comfortable at rest but ordinary activity causes symptoms 4
• Class III: Marked limitation, comfortable at rest but less than ordinary activity causes symptoms 4
• Class IV: Unable to carry on any activity without discomfort, symptoms present at rest 4

Common Pitfalls to Avoid

Do not diagnose unexplained cough until uncommon causes have been systematically excluded. 4 Many candidates fail to consider large airway disorders because imaging appears normal, but flow-volume curves and bronchoscopy are required 4.

For PSC diagnosis, do not perform ERCP as first-line investigation - MRCP should be preferred due to comparable accuracy without procedural risks. 4 ERCP is reserved only for equivocal MRCP findings or when MRCP is contraindicated 4.

In congenital heart disease cases, always assess for hemodynamically significant shunts by looking for chamber enlargement and sustained Qp:Qs ≥1.5:1. 4 A shunt not meeting these criteria should be described as small or trivial 4.

UK graduates have significantly higher pass rates (67%) compared to overseas graduates (26%), with ethnic minority UK graduates showing intermediate success rates (56%). 3 This emphasizes the importance of familiarity with UK clinical practice patterns and examination expectations 3.