A ureteral stone or calculi is a kidney stone that has moved down into the ureter. The stone begins as a tiny grain of solid matter deposited where urine collects in the kidney. When the urine flows out of the kidney, the grain of undissolved material is left behind. Over time, more undissolved material is deposited and the stone becomes larger. Some kidney stones remain in place, continuing to grow larger.
The majority of stones are eventually carried out of the kidney into the ureter. Most stones enter the ureter when they are still small enough to move down into the bladder. From there, they pass out of the body with urination. For some stones that get caught in the ureter during passage to the bladder, urinary obstruction due to impaction of the stone can occur. This is often due to stones larger than 5 mm in size. If these stone fragments do not pass spontaneously after conservative therapy, laser lithotripsy may be required.
Laser lithotripsy uses the energy of a pulsed Holmium:YAG@2100nm laser for the stone fragmentation. It is usually performed under general anesthesia by introducing an ureteroscope through the urethra, into the bladder, and up the ureter. With direct visualization of the stone within the ureter, a laser fiber can be used to fragment the stone into smaller pieces. After procedure, a small amount of bleeding in the urine is expected but overnight stay in the hospital is typically not required.
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