Phase 2: Systematic Interpretation and Common Diagnostic Pathways
What Phase 2 tests
Phase 2 shifts from mechanism to pattern recognition and structured reporting. You must be able to run a search pattern for each major system and justify the next investigation. Concepts to name explicitly: the chest radiograph review (position, inspiration, rotation, then airway, breathing, circulation, diaphragm, edges, fields); the abdominal CT approach (bowel wall, mesentery, solid organs, vessels, bones, free gas/fluid); the brain CT approach (grey-white differentiation, symmetry, cisterns, blood, midline shift); and the plain-film fracture description (site, pattern, displacement, angulation, articular involvement). Know the classical signs: pneumothorax, pneumoperitoneum, small-bowel obstruction, appendicitis on ultrasound/CT, and the red-flag features of a malignant bone lesion (wide zone of transition, cortical destruction, periosteal reaction, soft-tissue component). Understand when contrast phases matter - arterial, portal venous, delayed - and why a non-contrast CT head is first-line in acute stroke.
Traps
Stems often describe a normal variant to test overcall: azygos fissure, calcified granuloma, or a prominent cisterna magna. Another trap is the 'most appropriate next step' question where the answer is not the definitive test but the safest immediate one - for example, stabilise and image rather than jumping to MRI. Beware negative findings presented as reassuring when a subtle sign (e.g. loss of the insular ribbon) is the real answer.
Worked example
A 24-year-old with sudden pleuritic pain and a tall, thin build: describe the film, look for a visible pleural line with absent lung markings distal to it, assess for mediastinal shift (tension), and state that a small pneumothorax may need expiratory or lateral decubitus views. Rule of thumb: describe, then synthesise, then recommend - never recommend before describing.