All of the following are true about pleural effusion, Except:

Answer is A (Horizontal fluid level) Succussion splash & horizontal fluid levels are features of hydropneumothorax & not pleural effusion. Pleural efusions are associated with decreased chest movements, decreased lung volumes and may be associated with diminished hea sounds Fluid level is typically concave & succession splash is not demonstable Succussion splash is a feature of Hydropneumothorax and not pleural Effusion Fluid movement in a cavity devoid of air is silent. When the cavity contains both air and fluid, body movements cause a splash audible to the patient and examiner - succussion splash A succussion splash in the thorax suggests a hydropneumothorax A succussion splash in the thorax may also result from a fluid filled stomach herniating into the thorax through a diaphragmatic hernia A succussion splash in the thorax in theory might be produced by a lung abscess, but in practice this almost never occurs because the pus is so thick that it does not splash. Horizontal Fluid level is a feature of Hydropneumothorax Pleural effusion presents with a concave fluid level (concave upper edge) Presence of horizontal fluid level indicates the presence of associated air in the pleural cavity and suggests a diagnosis of Hydropneumthorax