What am I looking at?

In order to recognize pleural effusions, it is first important to note the following normal anatomic structures and their sonographic appearance at the costophrenic interface.

Lung:

• Cephalad to the diaphragm
• Normally air filled, causing gas scatter: grey homogenous haze obscuring deep structures

Diaphragm:

• Smooth, layered, rounded hyperechoic line, ~5mm thick
• Moves with respiration

Solid Organ (liver/spleen):

• Homogenous echogenic structure
• Caudad to the diaphragm
• Smooth, well demarcated borders

Video 1: Normal anatomy at posterior axillary line