Rim sign (chronic hydronephrosis)

Last revised by Joshua Yap on 28 Feb 2023

The rim sign can be seen in association with chronic hydronephrosis

In patients with chronic hydronephrosis, in all forms of contrast-enhanced imaging of the obstructed kidney, enhancement may occur in the residual, but markedly atrophic, renal parenchyma, surrounding the dilated calyces and renal pelvis 1,2.

The inner margin of this hydronephrotic rim is concave toward the renal hilum, and enhancement of the cortical columns between the dilated collecting system elements may be seen. The unopacified urine within the dilated system may act as a negative pyelogram.

See also

Other rim signs in radiology:

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