Comet tail sign (phleboliths)

Last revised by Mohammadtaghi Niknejad on 17 Aug 2022

The comet tail sign (in urological imaging) helps distinguish a ureteric calculus from a phlebolith and strongly favors the latter. 

The sign refers to a tail of soft tissue extending from a calcification, representing the collapsed/scarred/thrombosed parent vein. When well seen, it is said to have a positive predictive value of 100% 1.

See also

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Cases and figures

  • Figure 1: comet tail (photo)
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