What Needs to Know about Urolithiasis

FURTHER READING: KIDNEY STONE MANAGING, from MAYO CLINIC

Kidney Stones Managing

Treatment alternatives for kidney stones can be as simple as waiting for the stone to pass or can involve medical or surgical treatment. Most often, kidney stone removal is scheduled ahead of time; it isn't usually an emergency. In rare instances, an emergency procedure may be needed to surgically drain any urine that has accumulated behind a kidney stone to help relieve pain and to minimize the risk of infection.

The size and location of the stone and the patient's preference and pain tolerance are key factors for selecting a treatment alternative. Most small kidney stones will pass through the urinary tract unaided. However, it's difficult to predict how painful passing a kidney stone will be. Some people prefer waiting for the stone to pass rather than undergoing a medical or surgical procedure for removal; others find this approach too unpredictable and anxiety-provoking. Urologists can facilitate stone passage using extracorporeal shock wave lithotripsy to break apart smaller kidney stones that are not located in the lower regions of the ureter (the tube from the kidney to the bladder). Small stones located in the lower third of the ureter require the use of a ureteroscope. Larger stones are removed using a surgical procedure called percutaneous nephrolithotomy.

This section includes information on:

·         Watchful Waiting

·         Extracorporeal Shock Wave Lithotripsy (ESWL)

·         Percutaneous Nephrolithotomy (PNL)

·         Ureteroscopic Stone Removal

Watchful Waiting

Even though 85 percent of kidney stones are small enough to pass during urination, fewer than 50 percent of patients chose this option. A person with a normal-size ureter can usually pass a kidney stone with a diameter less than 5 mm (about 3/16 of an inch) without significant pain or risk of kidney damage. Infection and blockage of the urinary tract are the primary complications associated with waiting for a kidney stone to pass. Long-term blockage of the urinary tract can lead to kidney damage. If the warning signs of a urinary tract infection or blockage develop—fever or chills and intense pain—it's time to seek medical attention.

Most stones pass within 72 hours after the symptoms first appear. However, for some people, it can take weeks to pass a kidney stone, with an unpredictable pattern and degree of pain. Shape and location of the stone may give clues to how easily the stone will pass. Some people experience only momentary and tolerable pain; for others, passing the stone can trigger intense and persistent pain. Because of this unpredictability, most patients prefer to have their kidney stone removed by a urologist rather than wait for passage.For other people, waiting for a kidney stone to pass may not be practical. For example, airline pilots or heavy-quipment operators may want to avoid a sudden attack of incapacitating abdominal pain at work.

The guidelines for waiting for a kidney stone to pass include:

·         Drink at least 3 quarts of water per day.

·         Stay physically active.

·         Use pain medication as recommended or prescribed by your doctor.

·         Urinate through a strainer to recover the stone for analysis.

·         If fever or chills develop or symptoms (pain) worsen, seek out immediate medical attention.

Extracorporeal Shock Wave Lithotripsy (ESWL)

Extracorporeal shock wave lithotripsy is used to treat 80 to 90 percent of kidney stones. Kidney stones smaller than 1.5 cubic centimeters (roughly the size of a marble) that are not located in the lower third of the ureter are usually treated with ESWL. ESWL is a noninvasive procedure that uses shock waves to break up the kidney stone in situ (in place).

Shock waves are zones of high pressure that travel through fluid, retaining their energy until a solid object is encountered. Shock waves are used to treat kidney stones because they can pass through the bones and tissues of the body without dissipating any energy, yet pulverize a kidney stone on impact. Once the stone has been crumbled, the fragments pass through the urinary tract and out of the body. For kidney stones located in the lower third of the ureter, the pelvis bone interferes with the imaging of the stone required for this procedure, so these stones are removed using a ureteroscope.

Preparing for the procedure may require limiting food and water, depending on the type of sedation to be used. The shock waves can be painful, so the procedure is usually performed using full sedation or general anesthesia, but on an outpatient basis. The procedure begins by either partially submerging the patient in a tub of water while he or she sits in a chair or having the patient recline on a water-filled cushion. Shock waves are then directed at the kidney stone while X-rays or ultrasound are used to monitor the location and status of the stone. The shock waves pound the stone until it crumbles and is passed in the urine. This usually requires 1,000 to 2,000 shock waves and takes approximately 30 minutes. Shock waves are loud, so patients wear earphones to protect their hearing during the procedure.

Recovery is quick; usually patients are able to leave the treatment center within a few hours. Normal activity can be resumed in two to three days. Fluid intake is encouraged to help pass the stone fragments. Some stone fragments may be too large to pass, and additional treatment with ESWL may be necessary. The likelihood of needing additional treatment depends largely on the experience of the urologist and the capability of the equipment to emit high-energy shock waves. Approximately 2 to 25 percent of people undergoing ESWL will need additional treatment to remove the kidney stone.

Approximately 1 million people have had this treatment since it was approved by the Federal Drug Administration in 1985. Documented side effects from this procedure include blood in the urine for a short time, minor bruising on the back or abdomen, and some discomfort as the stone fragments pass through the urinary tract. Recent data suggest a potentially increased incidence of diabetes or hypertension in patients who have undergone ESWL. Further research is underway to assess this potential link between ESWL and diabetes or hypertension.

Percutaneous Nephrolithotomy (PNL)

Percutaneous nephrolithotomy is used to remove kidney stones 2 cubic centimeters or larger (2 cubic centimeters is a little larger than a marble). In PNL, the urologist breaks up and removes the kidney stone through a small incision in the side using a nephroscope. A nephroscope is a telescope about the diameter of a person's pinkie finger used to examine and perform procedures on the kidneys. This procedure is approximately 95 percent effective at removing kidney stones when performed at hospitals experienced with it.

The procedure begins with a radiologist inserting a narrow guide wire, also known as a catheter, through a small incision (2 to 3 mm long, less than 1/8 of an inch) in the skin. The catheter is inserted using fluoroscopy, a specialized X-ray technique, to help guide the catheter through the kidney into the ureter while the patient is sedated. Once the guide wire is in place, the patient is moved into the operating room where the PNL procedure is completed under general anesthesia. Dilators are inserted along the guide wire to gradually enlarge the opening so it can accommodate the nephroscope. The urologist inserts the nephroscope, which is equipped with a fiber-optic light, to visualize the stone. All stones and fragments are removed through the nephroscope during the procedure, which usually takes about 15 to 45 minutes; none are left to pass through the urinary tract. If necessary, an ultrasonic probe or laser can be inserted through the nephroscope to break up the stone. A catheter is left in place for several days following the procedure to drain the kidney.

This procedure usually involves one to two days of hospitalization. During this time, additional imaging may be performed to confirm that the stones have been removed. If any stones remain, a nephroscope will be used to remove them; the procedure requires sedation only at this time. Once the stones have been removed, the catheter will be removed and the patient will be discharged from the hospital. Full recovery usually requires one to two weeks.

Ureteroscopic Stone Removal

If the kidney stone has moved from the kidneys down into the ureter, the tube that carries urine from the kidney to the bladder, ureteroscopy can be used to remove it. A urologist can use either extracorporeal shock wave lithotripsy or ureteroscopy to remove stones from the ureter. The technique chosen depends on the type of ESWL machine available and the preference and skills of the urologist.

A ureteroscope is a small, flexible telescope that is used to examine and perform procedures on the ureter. A ureteroscope enters the body through the urethra, following it into and then through the bladder to reach the ureter. A ureteroscope is equipped with fiber-optic lights and small working channels through which devices can be passed to break up the kidney stone, snare it, and remove it. If the stone is large, the urologist may use ultrasound, laser, or a technique called electrohydraulic lithotripsy to shatter the stone prior to removal. After the procedure, a small stent (tube) may be inserted in the ureter for a few days to minimize swelling and promote healing.

Typically the procedure is performed on an outpatient basis with most people returning to work within a few days. Although an incision is not needed, most patients undergoing this procedure receive local or general anesthesia. Preparing for anesthesia may involve abstaining from food and beverages prior to the exam; check with your healthcare provider for exact restrictions.

Ureteroscopy is not without risk; potential complications are perforating the ureter or causing scar tissue to develop. The risk of complication increases if the stone has been embedded in the wall of the ureter for more than two months.

Last reviewed on 10/13/09