Lithotripsy is a procedure used to treat kidney stones that are too large to pass through the urinary tract. It works by sending focused ultrasound energy as shock waves directly to the stone. The shock waves break a large stone into smaller stones that will pass through the urinary system. Lithotripsy lets people with certain types of kidney stones possibly not need surgery. To find the stone, doctors use fluoroscopy. This is a series of moving X-ray pictures. Doctors may also use ultrasound to find the stone.

There are two types of shock wave technology. In the original method, the person is placed in a tub of water through which the shock waves are sent. These are guided by X-rays or ultrasound. This method is still in use. In a second method, the person lies on a soft cushion and the shock waves pass through that. This method is more common.

When substances normally excreted through the kidneys stay in a kidney, they may crystallize and harden into a kidney stone. If the stones break free, they can get stuck in the narrower passages of the urinary tract. Some kidney stones are small or smooth enough to pass easily through the urinary tract without discomfort. Other stones may have rough edges or grow as large as a pea or more. These can cause great pain as they move through or block the urinary tract. The areas that are more prone to trapping kidney stones are the bladder, ureters, and urethra.

Most kidney stones are small enough to pass without treatment. But in about 1 in 5 cases, the stone is greater than 2 cm (about 1 inch) and may need treatment. Most kidney stones are made of calcium. But there are other types of kidney stones. Types of kidney stones include:

• Calcium stones. Calcium is a normal part of healthy eating and is used in bones and muscles. It's normally flushed out with the urine. Excess calcium not used by the body may mix with other waste products to form a stone.
• Struvite stones. Struvite stones are made of magnesium, phosphate, and ammonia. They may form after a urinary tract infection.
• Uric acid stones. Uric acid stones may form when urine is too acidic. This can happen when you have gout or certain cancers.
• Cystine stones. These stones are made of cystine. Cystine is one of the building blocks that make up muscles, nerves, and other parts of the body.

When kidney stones get too large to pass through the urinary tract, they may cause severe pain and may block the flow of urine. This can cause infection and problems with how the kidneys work.

There may be other reasons for your doctor to suggest lithotripsy.

Risks of lithotripsy may include:

• Bleeding around the kidney. It's common for there to be small amounts of blood in the urine for a few days after the procedure.
• Infection.
• Blockage of the urinary tract by pieces of stone. This can lead to kidney failure in extreme cases.
• Pieces of stone that aren't passed from the body may need more lithotripsy treatments. Obesity and intestinal gas may interfere with a lithotripsy treatment.
• Excessive pain or discomfort.

Not everyone is able to have lithotripsy, including:

• Those who are pregnant. This treatment is unsafe for a fetus.
• People who have a large aortic aneurysm.
• People with certain bleeding conditions.
• Those with certain skeletal deformities that prevent accurate focus of shock waves.

Tell your doctor if you have a heart pacemaker. Lithotripsy may be done on people with pacemakers with the approval of a cardiologist and by using certain precautions. Be sure to discuss any concerns with your doctor before the procedure.

You may want to ask your doctor about the amount of radiation used during lithotripsy. It is a good idea to keep a record of your radiation exposure, such as previous scans and other types of X-rays, so that you can tell your doctor. Radiation risks may be related to the cumulative exposure over time.

• Your doctor will explain the procedure, and you can ask questions.
• You'll be asked to sign a consent form that gives your permission to do the procedure. Read the form carefully and ask questions if something isn't clear.
• Your doctor will ask about your health history. They will also do a physical exam to make sure you're in good health before having the procedure. You may have blood tests or other tests.
• You may need to fast before the procedure. You'll be given instructions on how many hours to fast before the procedure if needed.
• Tell your doctor if you're pregnant or think you may be. Those who are pregnant shouldn't have lithotripsy because of the risks to the fetus.
• Tell your doctor if you're sensitive to or allergic to any medicines, latex, tape, or anesthesia.
• Tell your doctor of all medicines (prescription and over-the-counter) and herbal supplements that you're taking.
• Tell your doctor if you have a history of bleeding disorders or if you're taking any anticoagulant (blood-thinning) medicines, aspirin, or other medicines that affect blood clotting. You may need to stop these medicines before the procedure.
• You may get a sedative or anesthetic before the procedure to help you relax.
• Based on your medical condition, your doctor may ask for other specific preparations.

Lithotripsy may be done on an outpatient basis or as part of a hospital stay. Procedures may vary depending on your condition and your doctor's practices.

Generally, lithotripsy follows this process:

1. You'll need to remove any clothing, jewelry, or other objects that may interfere with the procedure.
2. If you need to remove your clothing, you'll put on a hospital gown.
3. An I.V. (intravenous) line will be inserted in your arm or hand to give you fluids and medicines.
4. You may get medicine to help you relax or medicine to stop pain to make sure that you stay comfortable, still, and pain-free during the procedure.
5. After the sedation has taken effect, you'll be put on a water-filled cushion or immersed in a water-filled tub.
6. After the stone has been found with fluoroscopy or ultrasound, you'll be positioned for the best access to the stone.
7. If you're awake during the procedure, you may feel a light tapping feeling on your skin.
8. A series of shock waves will be sent to shatter the kidney stone.
9. The stone will be kept track of by fluoroscopy or ultrasound during the procedure.
10. The medical staff may place a stent in the ureter before lithotripsy to help keep the passage open so stone pieces and urine can pass easily.
11. Once the stone fragments are small enough to pass through the urinary system, the procedure will end.

Talk with your doctor about what you'll experience during your lithotripsy procedure.

After lithotripsy, you'll be taken to the post-anesthesia recovery room for observation. Once your blood pressure, pulse, and breathing are stable and you're alert, you will be taken to your hospital room or discharged home. Plan to have someone give you a ride home. You shouldn't drive for at least 24 hours after getting sedatives for the procedure.

You may go back to your usual diet and activities unless your doctor tells you otherwise. Certain stones can be prevented by dietary and lifestyle changes.

You will be encouraged to drink extra fluids to dilute the urine and reduce the discomfort of passing stone pieces.

You may notice blood in your urine for a few days or longer after the procedure. This is normal.

You may notice bruising on the back or belly. This is also normal.

Take a pain reliever for soreness only as recommended by your doctor. Don't take aspirin, ibuprofen, or certain other pain medicines. They may increase the chance of bleeding.

You may be given antibiotics after the procedure. Be sure to take the medicine exactly as prescribed.

You may be asked to strain your urine so that remaining stones or stone pieces can be sent to the lab for testing.

A follow-up appointment will be scheduled within a few weeks after the procedure. If a stent was placed, it may be removed at this time.

Contact your doctor right away if you have any of the following:

• Fever, chills
• Burning with urination
• Urinary frequency or urgency
• Extreme lower back pain

Your care team may give you other instructions after the procedure, depending on your particular situation.

Before you agree to the test or the procedure, make sure you know:

• The name of the test or procedure.
• The reason you are having the test or procedure.
• What results to expect and what they mean.
• The risks and benefits of the test or procedure.
• What the possible side effects or complications are.
• When and where you are to have the test or procedure.
• Who will do the test or procedure and what that person's qualifications are.
• What would happen if you did not have the test or procedure.
• About any alternative tests or procedures to think about.
• When and how you will get the results.
• Who to call after the test or procedure if you have questions or problems.
• How much you will have to pay for the test or procedure.