Intrarenal arteriovenous fistula occurs as a consequence of simultaneous laceration of a renal artery branch and an adjacent vein during biopsy.

The majority of these lesions are small, are clinically insignificant, and usually resolve spontaneously; thus, the frequency of this complication is unknown. When lesions are sizable, marked arteriovenous shunting may result in renal ischemia. When symptomatic or large, intrarenal arteriovenous fistulas may be effectively treated with embolization .

At US an anomalous ectatic intrarenal vascular structure may be seen but color Doppler immediately identifies the lesion as vascular.  If color Doppler gain is steadily reduced to the point where normal renal blood flow disappears, the lesion will remain like a flashing beacon.

On colour flow Doppler analysis the fistula appears as a mosaic, a focal irregular combination of colors with aliasing due to high speed and turbulence of the flow.