Ureterovesical junction stone
We have previously talked about ureteral jets and the twinkle artefact. Here is an excellent clip shared by Dr. Robert Jones demonstrating twinkle artefact in the right distal ureter region suggestive of an ureterovesical junction stone. Shadowing from the stone is not always prominent in this region and twinkle artefact on color Doppler helps to make the diagnosis. Note the strong ureteral jet on the left compared to the right corroborating with obstruction on the right.
Take home point: Always look for the cause of hydronephrosis and utilize color Doppler to identify twinkle artefact when you see something suspicious for a stone.