A supine portable chest radiograph of a trauma patient shows unusual lucency at the right costophrenic angle, with the angle appearing abnormally deep and its margin unusually sharp, extending along the lateral chest wall. What does this 'deep sulcus sign' indicate?

• A Pleural effusion
• B Basal bullous emphysema
• C Pneumomediastinum
• D Pneumothorax ✓

Explanation

In the supine position intrapleural air collects anteriorly and basally rather than apically, producing a lucent, deepened and sharply outlined costophrenic sulcus. This is the deep sulcus sign of pneumothorax on a supine film. An effusion would produce basal opacity with blunting of the angle rather than lucency, and a bulla produces a thin curvilinear wall without extension of the sulcus, which distinguishes both distractors.

Reference: Grainger and Allison's Diagnostic Radiology, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.