Chest X-ray interpretation — spontaneous pneumothorax

PLAB 2 & PRES 3 · respiratory / data interpretation · medium · 10 minutes

Candidate brief

You are an FY2 doctor in the emergency department. Mr Liam O'Connor, 26, developed sudden right-sided chest pain and breathlessness an hour ago while playing five-a-side football. He is alert and uncomfortable but stable. Observations: respiratory rate 24/min, SpO2 95% on air, pulse 98/min, BP 122/76 mmHg, temperature 36.8 °C. His erect chest X-ray is described below (the image itself will be shown to the AI patient as this description): Erect PA chest X-ray, adequate inspiration and penetration, not rotated. On the RIGHT: a thin, well-defined visceral pleural line running parallel to the chest wall from apex to base; lateral to this line there is a radiolucent (black) area completely devoid of lung markings occupying roughly the outer third of the hemithorax; the right lung is partially collapsed toward the hilum. Interpleural distance at the level of the hilum approximately 3 cm. No mediastinal shift; the trachea is central; the right hemidiaphragm is not depressed. No pleural fluid level. The LEFT lung is fully expanded and clear. No rib fractures; no surgical emphysema; heart size normal. Please interpret the X-ray, correlate it with the patient, and state your management plan.

What examiners look for

A pneumothorax is a line and an absence: a visceral pleural edge with no lung markings beyond it. Train your eye to follow the pleura around every breathless patient's film, because the diagnosis is missed by looking at the lung instead of its border. Measure it the way the guideline measures it — interpleural distance at the level of the hilum, 2 cm the "large" threshold — and then remember the modern BTS lesson: size informs, symptoms decide. A large pneumothorax in a comfortable patient and a small one in a breathless patient are not managed by the tape measure alone. Tension is a clinical diagnosis wearing radiological clothes: tracheal shift, mediastinal displacement, a depressed diaphragm and a deteriorating patient. Its absence on this film — central trachea, no shift, stable man — is as much a finding as the pneumothorax itself, because it is what keeps you out of resus with a decompression needle. Aspiration before drain is the primary-pneumothorax default: needle aspiration succeeds in the majority, hurts less, and often avoids admission; a drain is the answer to failed aspiration, not a first reflex. Knowing your branch points before you start — aspirate, re-image, reassess, then decide — is the whole procedure. The consultation after the procedure is the recurrence prevention: smoking and cannabis, the absolute flying ban until proven resolved (plus the interval), diving's near-absolute contraindication, and a follow-up film booked before he leaves. Pneumothoraces come back in roughly a quarter to a third of patients; the ones who return safely are the ones who were told exactly when to return in a hurry. And notice who this happens to: tall, thin, young, smoking at weekends, mid-football match. Pattern recognition is not stereotyping — it is what makes you look for the pleural line in the first place.

Guideline references

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