Reverberation and comet-tail artefacts on ultrasound: what they are
9-year-old cat with chronic vomiting. On abdominal ultrasound, beneath the wall of a jejunal loop containing gas there is a very hyperechoic line followed by several parallel, equally spaced lines of decreasing intensity, with a 'dirty' shadow behind.
What do those lines represent?
chevron_right Show answer and explanation
A. A reverberation artefact: the ultrasound bounces repeatedly between the gas–tissue interface and the transducer
Correct. Gas reflects almost the whole beam; echoes that bounce several times are displayed as equally spaced copies at greater depth. When the reverberations are very close together they form a comet tail.
B. A mineralised foreign body with acoustic shadowing
A mineral foreign body or calculus produces a hyperechoic surface with a clean (anechoic) acoustic shadow, not repeated equally spaced lines with a dirty shadow.
C. A mirror image of the intestinal wall
A mirror image duplicates an entire structure on the far side of a strong curved reflector (typically the diaphragm); it does not create repeated parallel lines.
D. Thickening of the muscular layer of the wall, consistent with lymphoma or chronic enteropathy
Wall layers are assessed in the wall nearest the transducer. What appears beneath the gas is not real tissue: gas prevents visualisation of the far wall and the contents.
lightbulb Key takeaway
'Clean' shadow = mineral or bone (absorption/reflection); 'dirty' shadow with reverberation = gas. Comet tails appear with small gas or metal interfaces. To see beyond gas, change the window or gently compress the loop.
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Updated: October 31, 2026 · Educational content for veterinary professionals. It does not replace current clinical guidelines or the judgement of the attending veterinarian.