The condition of formation and deposition of stones in the kidneys is called Nephrolithiasis. These stones are called Renal Calculi. Sometimes these stones dislodge from the kidneys and descend into the ureters and the urinary bladder. Some stones are small enough to pass out of the urinary bladder through the urethra in the urine. Others might be large enough to block any part of the ureter or may get stuck in the urinary bladder and cannot pass through the urethra. These stones need to be surgically removed when flushing them out is not possible. This is performed by a procedure known as Ureteroscopic Lithotripsy.