Perinephric stranding

A CT finding of increased attenuation within the perinephric fat, reflecting edema, inflammation, or infiltration in the perirenal space surrounding the kidney. Possible causes are pyelonephritis, perinephric abscess, post-renal obstruction (ureterolithiasis, bladder outlet obstruction), renal trauma, retroperitoneal fibrosis, or aging (normal anatomical finding in older adults).