Subpulmonic effusion

 Pleural effusion that remains in the infrapulmonary location without spilling into the costophrenic sulci or extending up the chest wall. 

 Characteristics in CXR:

a) apparent elevation of one or both diaphragms 

b) Apex of the diaphragm is more lateral than usual 

c) Apparent diaphragm slopes much more sharply towards lateral costophrenic angle 

d) if subpulmonic effusion is on left side- lower border of lung is separated farther at its junction with infrapulmonary effusion 

e) lower lobe vessels may not be seen