Roentgen Diagnosis of Small Pleural Effusions

The early diagnosis of small pleural effusions was greatly advanced with the introduction of the roentgen method of examination. With the rapid improvement in roentgenoscopic and roentgenographic technic, accurate diagnosis can now be made at a relatively early stage. It has been estimated by Emerson¹that it is almost impossible, by physical diagnostic methods, to detect a pleural effusion less than 250 cc. in amount, and usually effusions less than 400 cc. cannot be diagnosed. Ganter²believes that less than 400 cc. of fluid in the pleural cavity can hardly be diagnosed by the usual methods of roentgen examination, although he was able to detect 150 cc. when pneumothorax also was present. The commonly accepted earliest signs of free pleural effusion are an obliteration of the costophrenic angle, some flattening of the dome of the diaphragm and some loss of detail at the base of the lung on