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 travel through the ureters (narrow tubes that connect the kidneys and the bladder) to exit the body during urination.

Symptoms of a kidney stone include severe pain in the flank, which is felt just below the rib cage and above the waist, usually on only one side of the back. 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.

A kidney stone is usually treated at home with pain medicine until it has passed. Make sure you drink enough fluid so that you don't get dehydrated. Most of the time, the stone will pass in a few days. If the stone seems unlikely to pass on its own or is causing severe pain, treatment options include a shock wave treatment (lithotripsy), which can break up a large stone into smaller pieces that are easier to pass, or, in very rare cases, surgery.

If a stone is stuck in a ureter, a long, thin viewing tool (ureteroscope) can be passed through the urethra and bladder to the ureter. The stone may be taken out using a tiny basket on a wire passed through the ureteroscope. The stone can also be broken up using laser and then flushed out of the ureter with fluids inserted through the ureteroscope.

There are four main types of kidney stones, and they can be as small as grains of sand or as large as a golf ball. Kidney stones occur most often in adults and are rare in children.