The severity of kidney stones depends on the size of the stones and their location. For example, stones within the kidney parenchyma, if not large and not moving, generally do not cause much trouble.

However, if the stones block the area of the renal pelvis and calyces, or even move downward to block the ureter, causing the urine produced by the kidneys to not be excreted smoothly, it will cause the patient to experience renal colic. This type of pain is very intense, radiating to the back and causing abdominal pain, as well as pain in the perineal area. Patients often may also experience fever and other clinical symptoms. Prolonged obstruction of the urinary system can lead to renal failure, which is quite dangerous.