<unk>  is sometimes a complication of kidney stones, which can be a source of persisting infection. It may also occur spontaneously. It can occur as a complication of hydronephrosis or pyelonephritis.
Pyonephrosis
Hydronephrosis
Pyelonephritis
Glomerulonephrosis
Ureteritis
Renal colic
Hemorrhagic cystitis
Oophoritis