Hello, Kidney stones are small or large calcified bodies that originate in kidney only. They usually stay at one place but may move in kidney, ureter (pipe that joins kidney with urinary bladder), bladder and then may be out of the body. They indicate their presence in urine as high mineral content, pus cells or red blood cells (microscopic blood). We have two kidneys in our bodies. They lie on the side and little back side. The ureters emerge from kidney and come forward to join bladder in the pelvic area. When you have kidney stones and they move in the kidney, they kind of impinge on the kidney tissue or ureter wherever they are and cause pain. So you feel pain in the side of the body or radiating pain that starts in the back and migrates forward. If the stones are small, doctor usually advises to drink lot of water and fluids and the stone passes out of the body through urine. In case of bigger stones, like the one you have, it is possible that the stone sometimes get stuck in the thinner parts of ureter and causes a lot of pain. Due to the big size, chances are less that they can pass easily through urine. So in your case, either the stone needs to be removed surgically or broken into small pieces that can easily pass through bladder and out of the body. Surgery is usually not performed due to other advances in technology and inventions of safe technologies. Lithotripsy is the process that uses ultrasound shock waves to break bigger stones into smaller pieces and facilitate their way out of the body. Urologists have the specialized skills and equipments to perform such procedures. Hence, you are referred by your doctor to a urologist. I hope this explains your condition in simpler terms. Thank you for choosing HealthCareMagic. I wish you feel better soon. Thanks, Dr. Viraj Shah