Dec 22, 2009
Lithotripsy is a therapeutic medical procedure used to disintegrate stones (calculi) in the urinary tract and kidneys. Extracorporeal shock wave lithotripsy (ESWL) uses shock waves generated outside the body and is non-invasive. Intracorporeal shock wave lithotripsy (ISWL) delivers shock waves through a specially designed scope used for the urinary tract (ureteroscope) and kidneys (nephroscope) and is a minimally invasive procedure. Ultrasound lithotripsy also uses a scope to deliver ultrasonic waves (mechanical vibrations) and is minimally invasive.
Lithotripsy is used when a kidney stone is too large to pass on its own, or when a stone becomes stuck in a ureter (a tube which carries urine from the kidney to the bladder) and will not pass. Kidney stones are extremely painful and can cause serious medical complications, such as kidney damage, if not removed. Usually, stones smaller than 5 mm in diameter can pass without intervention, while stones larger than 7 mm in diameter require lithotripsy or the placement of a urethral or ureteral stent to help them pass. Stones larger than 10 mm require lithotripsy or surgery.
ESWL is a noninvasive alternative to open surgery (which is only very rarely performed for stones now) or percutaneous nephrolithotomy. ESWL is used in patients with stones less than or equal to 1 cm located in the kidneys or ureters. ISWL is a minimally invasive endoscopic technique that is used in patients with stones over 1 cm, with stones in the lower urinary tract, with impacted stones, and when ESWL is unsuccessful. Both ESWL and ISWL can also be used to fragment gallbladder and bile duct stones.
ESWL should not be considered for patients with severe skeletal deformities, patients weighing over 300 lbs (136 kg), patients with abdominal aortic aneurysms, or patients with uncontrollable bleeding disorders. Patients who are pregnant should not be treated with ESWL. Patients with cardiac pacemakers should be evaluated by a cardiologist familiar with lithotripsy. Lithotripsy may temporarily inhibit the pacemaker or cause circuit damage leading to erratic functioning or cessation of the pacemaker. The cardiologist should be present during the lithotripsy procedure in the event there are problems with the pacemaker.
Lithotripsy uses focused shock waves to fragment a stone in the kidney or the ureter. In ESWL, the patient is placed on a table in contact with a water-filled cushion; and a shock wave is generated, travels through the water, and shatters and fragments the stone. Older ESWL systems involved immersing the patient in a tub of water; but this space-consuming, awkward method has been replaced by water-filled cushions. Once the stone is fragmented, the resulting gravel is left to pass on its own; the patient may have been stented prior to the procedure to widen the urethra and or ureters to allow the fragments to pass easily and with less pain. In ISWL, a ureteroscope is inserted through the urethra and bladder and into the ureters, or a nephroscope is inserted, usually through an incision in the patient's back. Once the stone is located using the endoscope, an electrohydraulic, laser, or ultrasound lithotripter can be used to fragment the stone. In ISWL using an electrohydraulic lithotripter, a probe is inserted through the endoscope and against the stone, and shock waves are delivered by a generator. In laser ISWL,
a pulsed-dye laser is used to deliver laser energy through a fiber inserted through the endoscope and into the stone. Ultrasound ISWL uses a generator to produce mechanical vibrations delivered to the stone via a probe tip inserted through the generator. In ISWL, after the stone is fragmented, the pieces can be removed using a grasper or basket or left to pass on their own if they are small enough.
Prior to the lithotripsy procedure, a complete physical examination is done, including a urine analysis, followed by imaging tests to determine the number, location, and size of the stone or stones. A test called an intravenous pyelogram, or IVP, is often used to locate the stones and determine the degree of obstruction (blockage). An IVP involves injecting a dye (contrast medium) into a vein in the arm. This dye, which shows up on x ray, travels through the bloodstream and is excreted by the kidneys. The dye then flows down the ureters and into the bladder. The dye surrounds the stones, and x rays are then used to evaluate the stones and the anatomy of the urinary system. For those patients who are allergic to the dye, ultrasound, which uses focused sound waves, or computed tomography without contrast dye is performed. Blood tests are done to determine if any potential bleeding problems exist. For women of childbearing age, a pregnancy test is done to make sure the patient isn't pregnant; and elderly patients have an elctrocardiogram (ECG) done to make sure no potential heart problems exist. Some patients may have a stent placed prior to the lithotripsy procedure. A stent is a plastic tube placed in the ureter which allows the passage of gravel and urine after the procedure is completed.
Most patients have a lot of blood in their urine after the lithotripsy procedure. This is normal and should clear after several days to a week or so. Lots of fluids should be taken to encourage the flushing of any gravel remaining in the urinary system. The patient may be asked to urinate through a strainer and collect any stone fragments that pass for examination by the physician. Patients with stents may experience some discomfort during urination or during certain movements; this is normal. The patient should follow up with the urologist in about two weeks to make sure that everything is going as planned. If a stent
has been inserted, it is normally removed at this time. Patients may return to work whenever they feel able.
Occasionally, the ESWL procedure does not break stones into pieces small enough to pass. In these cases, an endoscope may be used to remove the pieces after the ESWL procedure.
Abdominal pain is not uncommon after lithotripsy, but it is usually not cause to worry. However, persistent or severe abdominal pain may imply unexpected internal injury. Colicky renal pain is very common as gravel is still passing. Other problems may include perirenal hematomas (blood clots around the kidneys); hemorrhage; pancreatitis (inflammation of the pancreas); damage to nearby organs and tissues (during ISWL); and obstruction by stone fragments. The most common complication is urinary tract infection, sometimes present prior to the procedure due to obstruction by stones. Prophylactic antibiotics are administered to treat infection. Other postprocedural complications sometimes associated with the administration of anesthetics include nausea, vomiting, and allergic reaction.
Lithotripsy is performed by a urologist or urologic surgeon, sometimes in conjunction with a radiologist, and with assistance from nursing staff for patient monitoring and medication administration during the procedure. The procedure may also be performed by a uroradiologist. If ISWL requires general anesthesia or conscious sedation, an anesthesiologist and/or nurse anesthetist may need to be present for the procedure. Because ESWL uses x rays to locate the stones, a radiologic technologist may be required to assist with operating the x-ray equipment.
Aneurysm—A dilation of the wall of an artery which causes a weak area prone to rupturing.
Bladder—Organ in which urine is stored prior to urination.
Bleeding disorder—Problems with the clotting mechanism of the blood.
Cardiologist—A physician who specializes in problems with the heart and its vessels.
Computed tomography—An imaging examination that uses x-rays to produce a cross-sectional image of the anatomical area of interest; used to image the urinary tract and kidneys to detect kidney stones.
ECG—Electrocardiogram; a tracing of the electrical activity of the heart.
Gravel—The debris which is formed from a fragmented kidney stone.
IVP (Intravenous pyelogram)—The use of a dye, injected into the veins, used to locate kidney stones. Also used to determine the anatomy of the urinary system.
Kidney stones—Also called calculi; hard masses that form in the urinary tract and which can cause pain, bleeding, obstruction, or infection. Stones are primarily made up of calcium and can vary in size from a few millimeters to over a centimeter and more in diameter.
Nephroscope—An endoscope, a thin flexible tube with optics, used to examine the kidneys and through which intracorporeal lithotripsy can be performed.
Percutaneous nephrolithotomy—A minimally invasive endoscopic procedure involving a small incision in the back through which a nephroscope is inserted to remove stones from the kidney; used in conjunction with ISWL and after unsuccessful ESWL.
Stent—A small, short plastic tubular device placed in the urethra or ureters to widen them in order for stones and stone fragments to pass easily.
Ultrasound—Sound waves used to determine the internal structures of the body.
Ureter—A tube which carries urine from the kidney to the bladder.
Ureteroscope—An endoscope, a thin flexible tube with optics, used to examine the ureters and through which intracorporeal lithotripsy can be performed.
Urethra—A tube through which urine passes during urination.
Urologist—A physician who specializes in problems of the urinary system.
Tanagho, Emil, and Jack McAninch, eds. Smith's General Urology. 14th ed. Norwalk, CT: Appleton and Lange Publishers, 1995.
Portis, Andrew J. and Chandru P. Sundaram. "Diagnosis and Initial Management of Kidney Stones." American Family Physician 63, no. 7 (April 1, 2001): 1329-1338.
Shagam, Janet Yagoda. "Extracorporeal Shock Wave Lithotripsy." Radiologic Technology 72, no. 2 (November-December 2000): 145-163.
American Urological Association. 1120 North Charles Street, Baltimore, MD 21201. 410-727-1100. <http://www.auanet.org>.
National Kidney Foundation. 30 East 33rd Street, Suite 1100, New York, NY 10016. (800) 622-9010. <http://www.kidney.org>.
Society of Urologic Nurses and Associates. East Holly Avenue, Box 56, Pitman, NJ 08071-0056. 609-256-2335. <http://suna.inurse.com/>.
Jennifer E. Sisk, M.A.
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