Kidney stones are made of salts and minerals in the urine that stick together to form small "pebbles." They are usually painless while they remain in the kidney, but they can cause severe pain as they break loose and travel through narrow tubes (ureters) to exit the body during urination.

Symptoms of a kidney stone include severe pain on one side of the back, just below the rib cage (flank pain). The pain may spread to the lower abdomen, groin, and genital area. Other symptoms include blood in the urine (hematuria), painful or frequent urination (dysuria), and nausea and vomiting.