The symptoms of kidney stones vary depending on the size and location of the stone, and whether there is associated hydronephrosis. If the stone inside the kidney is relatively small, most patients experience no discomfort, and it is generally discovered during an ultrasound examination at physical check-ups. However, if such a small stone falls into the ureter, it can irritate the ureteral walls and cause ureteral spasms, resulting in renal colic and, in some cases, hematuria. If the kidney stone is relatively large and causes kidney hydronephrosis or even pyonephrosis, the patient will experience sour swelling and pain in the waist on the side of the stone. If an infection occurs, symptoms such as chills and high fever may also appear.