the existence of an oesophagopleural fistula can be demonstrated by the discovery of food particles in the pleural aspirate , by direct visualisation during oesophagoscopy after instilling methylene blue into the pleural cavity , by barium swallow , or by identification of helium in the pleural space after swallowing a mouthful of helium .
C0032225
pleural
C0178802
pleural cavity