Lithotripsy is a procedure that uses shock waves to break kidney stones into small pieces so that they can pass out of the body in the urine more easily. Kidney stones are small, hard mineral deposits that build up in the urinary tract. These stones are usually about the size of a pea. Most kidney stones pass through the ureters, the tubes leading from the kidneys to the bladder, into the bladder and then on out of the body.
Who is a candidate for the procedure?
Anyone who has kidney stones that have led to obstruction, infection, or serious bleeding may be a candidate for lithotripsy.
How is the procedure performed?
One type of lithotripsy uses a machine called a lithotripter. This procedure, called bath immersion lithotripsy, breaks up stones in the kidney or upper ureters. It uses shock waves to pulverize the kidney stones, breaking them into smaller fragments, which are then easier to pass in the urine.
In preparation for the procedure, a person is usually given a mild sedative. Occasionally, general anesthesia is used. The individual is lowered into a large tub of water and submerged up to the shoulders. X-ray machines are used to locate the stones so that the body can be positioned properly. Shock waves are then sent through the water and the body.
The body has the same acoustic properties as the water, so it is not harmed by the shock waves. But the renal stones are so brittle that they respond to the shock waves by breaking apart. X-rays are taken throughout the procedure to check on the status of the stones. Usually 200 to 400, but sometimes as many as 1500, shock waves are needed to break down the stone.
The individual must wear protective headphones during this procedure because the shock waves produce a very loud sound. It usually takes about an hour, and no incision or hospitalization is needed. Stones that cannot be broken down by the lithotriptor may be broken down using other procedures.
One of these procedures is percutaneous ultrasonic lithotripsy. In this procedure, a small incision is made in the skin and a special scope is passed through it into the kidney. A small instrument is used to shoot ultrasound waves at the stone. The stone fragments are then removed through the same scope.
Endoscopic lithotripsy is another variation of lithotripsy. A small instrument is passed through the bladder and into the ureter. Attached is a unit that uses ultrasound waves to break down the stones.
Electrohydraulic lithotripsy also uses an instrument that is passed through the bladder. It sends out electrical charges to break up the stones in the urethra, the tube leading from the bladder to the outside of the body.
Mayo Clinic Family Health Book, DE Larson, 1996.