Transillumination using a cold light source is a quick bedside test to detect pneumothorax in neonates, especially in emergency settings or when a chest X-ray is unavailable. Procedure: \t1.\tDarken the room to enhance visibility. \t2.\tUse a fiber-optic cold light source (like a bright penlight or otoscope light). \t3.\tPlace the light against the lateral chest wall or just below the axilla. \t4.\tObserve the glow pattern on the opposite side. Interpretation: \t•\tPositive for pneumothorax: Exc

transillumination test