In the presence of highly reflective surfaces, echoes may reflect back and forth between the reflective surface and the ultrasound probe. This can cause the ultrasound screen to record and display multiple echoes on the screen. This ultrasound artifact is known as Reverberation Artifact.
Let’s use the highly reflective pleural line as an example below. The ultrasound waves that return after a single reflection represents the actual pleural line (white arrows/line in the figure below). All of the subsequent echoes (blue, green, and red arrows/lines) will take longer to return the probe and the ultrasound will interpret those as increased equidistantly spaced linear reflections. These other lines are also known as “A-lines” and are a form of reverberation artifact in normal lung.