A kidney stone is a calcification that occurs in the urinary tract. A urinary tract is meant not to pass stones but to pass liquid and when a stone comes down it usually will cause a great deal of pain. Generally they present with flank pain, pain in your back or side. Sometimes with some blood in the urine or with an infection.
Generally the pain is severe enough that you end up going to the emergency room to be checked because you are not sure what it is and you have a hard time controlling it. At the emergency room usually an X-ray, some blood work, and a urine test will be done to make the diagnosis.
Thankfully the majority of kidney stones are small enough that they do pass and most of them we do not have to treat surgically. About twenty percent of them end up requiring some type of surgical intervention. Today the most common type of intervention we would have for them is to use a procedure called Shock Wave Lithotripsy. We use an external source to create a shock wave that is indirected through the body to the stone itself and then the stone is broken up into a number of tiny little stones that pass on through with the urine flow.