Minimum fluid collection required for radiological detection of pleural effusion in lateral decubitus view is: September 2009: (A) 15 ml, (B) 25 ml, (C) 35 ml, (D) 45 ml
Answer is B. Ans. Amount of pleural fluid required to cause a blunted costophrenic angle discernible on chest radiography is more than 300 ml. A chest computerized tomography scan is more sensitive than a simple chest x-ray and is often used for assessment of loculated effusions because, in some instances, up to 500 cc of loculated fluid can be obscured behind the dome of the diaphragm