"dropout: loss of continuity of the reverberation pattern, may be increasing distally to the lens. Likely represents piezo element failure due to damage or manufacturing defect."
"delamination: disrupted reverberation pattern without complete signal loss. Usually less apparent, may also indicate damage, a weak piezo-element or manufacturing defect."
"non-uniformity: reverberation lines running non-parallel. As this also indicates image distortion, urgent replacement of the probe is warranted."
"lens wear: initially subtle change of the depth of reverberations peripherally. Usually caused by long term normal use. Should be followed to assess progression and consider timely replacement."
"The paper-clip method has been proposed as a simple, yet sensitive tool for monitoring probe quality. With this technique a small reflective object, such as a paper clip is moved along the surface of the probe lens, with the aid of a small amount of US acoustic gel. This technique can accentuate smaller dropouts of the reverberation pattern 2."