Kidney stones form when minerals precipitate out of urine in the urinary tract, most commonly inside the kidneys themselves. The stones can block urine flow, damage the kidneys, and be extremely painful.

Most kidney stones can pass out of the body in urine without any need for intervention beyond monitoring and pain management. Larger kidney stones, however, require medical intervention to get them out of the body. There are two basic ways to remove kidney stones other than the natural process. These are lithotripsy (literally, “breaking stones” from the Greek) and surgery.

Lithotripsy

In lithotripsy, the goal is to break the kidney stone into smaller pieces that the body will then be able to pass through the urinary tract normally and naturally.

There are two types of lithotripsy that are commonly used to break up kidney stones. One is extracorporeal shock wave lithotripsy (ESWL), also known as ultrasound lithotripsy or ultrasonic lithotripsy. The other is laser lithotripsy.

ESWL

ESWL uses ultrasonic pulses to break up the stone into smaller pieces. It’s called “extracorporeal” because the sound waves originate outside the body, with nothing inserted into the body except the sound waves themselves. Using ESWL requires that the kidney stone or stones be precisely located in the body. This can be done using medical imaging. An ultrasound scan can usually find kidney stones, but more precise location can be achieved using CT scan (computerized tomography), which employs computer enhancement and processing on X-ray information taken from multiple angles. Once the kidney stone is located, the patient is placed on a table with a fluid-filled cushion under the location of the stone. High-frequency sound pulses are directed into the stone, hopefully causing it to break into smaller pieces.

Laser Lithotripsy

If ESWL doesn’t work or can’t be attempted for some reason, lather lithotripsy is an option. This procedure uses laser light rather than sound to break up the kidney stones. It requires inserting a scope into the urinary tract (this is done by a urologist). The scope is used to locate the kidney stone. A laser fiber is then inserted up the scope’s working channel, and laser light is fired directly onto the stone. If all goes well, the stone breaks into smaller fragments that are then washed out through the urinary tract. Laser lithotripsy is considered minimally invasive surgery. It does not require making any incisions in the body and healing time is minimal to none. Laser lithotripsy is done under local or, more rarely, general anesthesia.

Surgery

If lithotripsy is inappropriate for treatment of a larger kidney stone or if it fails to break up the stone, surgical methods may be used to remove the stone. As with lithotripsy, there are two general categories of surgical treatment for kidney stones. These are uteroscopic surgery and nephrolithotomy.

Uteroscopic Surgery

As with laser lithotripsy, uteroscopic surgery employs a uteroscope which is inserted by a urologist into the urinary tract to precisely locate the kidney stone. (It should have been located with some precision already using medical imaging.) The scope guides the surgical procedures, which can include the placement of stents to allow urine to flow past the obstruction, as well as crushing or physical removal of the stone
itself.

Lithotomy

The most invasive form of kidney stone removal is lithotomy, which simply means removal of the stone. An incision is made in the body as close to the stone’s location as possible, and the stone is removed from the body through this incision. As this is a maximally-invasive treatment, it is used only for the largest stones that cannot effectively be treated with lithotripsy or uteroscopic surgery.