Kidney stones may cause blood in the urine when the kidney stone moves through the urinary tract, according to WebMD. It is possible that smaller kidney stones pass through the urinary tract without causing painful urination or blood in the urine.
Other symptoms of kidney stones moving through the urinary tract include severe pain in the back, belly or groin, and nausea and vomiting, according to WebMD. Kidney stones are usually diagnosed by a CT scan, X-ray, ultrasound, urinalysis or a blood test that indicates high levels of minerals involved in the formation of kidney stones. A small kidney stone can usually be passed without assistance, but larger stones may require drugs to relax the walls of the ureter.