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What Is a Urinary Tract Stone? A urinary tract stone is a hard deposit of minerals, acid and salt that clump together in the urine. Normally, the stones are small and pass unnoticed through the urinary tract. However, some stones become large, causing them to block the pathways where urine needs to travel. Stones may also develop and grow larger as they pass through the bladder, ureter and urinary tract. Stones may cause no symptoms, or they may cause severe pain in the ribs, hip, back and abdomen. We provide expert diagnosis and sophisticated treatment to remove stones and relieve pain. Types of Stones We Treat We treat: Bladder stones Kidney stones Ureter stones Stones in the urinary tract Stones (calculi) are hard masses that form in the urinary tract and may cause pain, bleeding, or an infection or block of the flow of urine. Tiny stones may cause no symptoms, but larger stones can cause excruciating pain in the area between the ribs and hips in the back. Usually, an imaging test and an analysis of urine are done to diagnose stones. Sometimes stone formation can be prevented by changing the diet or increasing fluid intake. Stones that do not pass on their own are removed with lithotripsy (the use of shock waves to break up those stones) or an endoscopic technique (the use of specialized tools to view and operate on internal organs). Urinary tract stones begin to form in a kidney and may enlarge in a ureter or the bladder. Depending on where a stone is located, it may be called a kidney stone, ureteral stone, or bladder stone. The process of stone formation is called urolithiasis, renal lithiasis, or nephrolithiasis. The Urinary Tract Every year, about 1 of 1,000 adults in the United States is hospitalized because of stones in the urinary tract. Stones are more common among middle-aged and older adults. Stones vary in size from too small to be seen with the naked eye to 1 inch (2.5 centimeters) or more in diameter. A large, so-called staghorn (because of its many projections that resemble a deer's antlers), stone may fill almost the entire renal pelvis (the central collecting chamber of the kidney) and the tubes that drain into it (calyces). A urinary tract infection may result when bacteria become trapped in urine that pools above a blockage. When stones block the urinary tract for a long time, urine backs up in the tubes inside the kidney, causing excessive pressure that can cause the kidney to swell (hydronephrosis) and eventually damage it. Kidney Stone in the Ureter Types of stones Stones are made of minerals in the urine that form crystals. Sometimes the crystals grow into stones. About 85% of the stones are composed of calcium, and the remainder are composed of various substances, including uric acid, cystine, or struvite. Struvite stones—a mixture of magnesium, ammonium, and phosphate—are also called infection stones, because they form only in infected urine. Causes of Urinary Tract Stones Stones may form because the urine becomes too saturated with salts that can form stones or because the urine lacks the normal inhibitors of stone formation. Citrate is such an inhibitor because it normally binds with calcium that is often involved in forming stones. Stones are more common among people with certain disorders (for example, hyperparathyroidism, dehydration, and renal tubular acidosis) and among people whose diet is very high in animal-source protein or vitamin C or who do not consume enough water or calcium. People who have a family history of stone formation are more likely to have calcium stones and to have them more often. People who have undergone surgery for weight loss (bariatric surgery) may also be at increased risk of stone formation. Rarely, drugs (including indinavir) and substances in the diet (such as melamine) cause stones. Symptoms of Urinary Tract Stones Stones, especially tiny ones, may not cause any symptoms. Stones in the bladder may cause pain in the lower abdomen. Stones that obstruct the ureter or renal pelvis or any of the kidney’s drainage tubes may cause back pain or renal colic. Renal colic is characterized by an excruciating intermittent pain, usually in the area between the ribs and hip on one side, that spreads across the abdomen and often extends to the genital area. The pain tends to come in waves, gradually increasing to a peak intensity, then fading, over about 20 to 60 minutes. The pain may radiate down the abdomen toward the groin or testis or vulva. Other symptoms include nausea and vomiting, restlessness, sweating, and blood or a stone or a piece of a stone in the urine. A person may have an urge to urinate frequently, particularly as a stone passes down the ureter. Chills, fever, burning or pain during urination, cloudy, foul-smelling urine, and abdominal swelling sometimes occur. Diagnosis of Urinary Tract Stones Symptoms Computed tomography (CT) Doctors usually suspect stones in people with renal colic. Sometimes doctors suspect stones in people with tenderness over the back and groin or pain in the genital area without an obvious cause. Finding blood in the urine supports the diagnosis, but not all stones cause blood in the urine. Occasionally, the symptoms and physical examination findings are so distinctive that no additional tests are needed, particularly in people who have had urinary tract stones before. However, most people are in so much pain and have symptoms and findings that make other causes for the pain seem likely enough that testing is necessary to exclude these other causes. Doctors need to differentiate stones from other possible causes of severe abdominal pain, including Peritonitis, which may be caused by appendicitis, ectopic pregnancy, or pelvic inflammatory disease Acute gallbladder disease (acute cholecystitis) Bowel obstruction Pancreatitis Dissecting aortic aneurysm Helical (also called spiral) CT done without the use of radiopaque contrast material is usually the best diagnostic procedure. CT can locate a stone and also indicate the degree to which the stone is blocking the urinary tract. CT can also detect many other disorders that can cause pain similar to the pain caused by stones. The main disadvantage of CT is that it exposes people to radiation. Still, this risk seems prudent when possible causes include another serious disorder that would be diagnosed by CT, such as an aortic aneurysm or appendicitis. Newer CT devices and methods that limit exposure to radiation are now commonly used. Ultrasonography is an alternative to CT and does not expose people to radiation. However, ultrasonography, compared with CT, more often misses small stones (especially when located in the ureter), the exact location of urinary tract blockage, and other, serious disorders that could be causing the symptoms. People who have recurrent kidney stones should consider limiting the number of CT scans they get to prevent excessive radiation exposure. X-rays of the abdomen expose people to much less radiation than does CT, but x-rays are much less accurate in diagnosing stones and can only show calcium stones. When doctors suspect the person has a calcium stone, x-rays are an alternative to confirm the presence of a stone or to see how far a stone has traveled down the ureter. Excretory urography (previously called intravenous urography or intravenous pyelography) is a series of x-rays taken after intravenous injection of a radiopaque contrast agent. This test can detect stones and accurately determine the degree to which they are blocking the urinary tract, but it is time-consuming and involves the risks of exposure to the contrast agent (for example, an allergic reaction or worsening of kidney failure). Doctors rarely use excretory urography to diagnose stones if CT or ultrasonography is available. Urinalysis is usually done. It may show blood or pus in the urine whether or not symptoms are present. Determining stone type For people with diagnosed stones, doctors often do tests to determine the type of stones. People should attempt to retrieve stones that are passed. They can retrieve stones by straining all urine through a paper or mesh filter. Stones found can be analyzed. Depending on the type of stone, urine and blood tests may be necessary to measure levels of calcium, uric acid, hormones, and other substances that may increase the risk of stone formation. Prevention of Urinary Tract Stones In a person who has passed a calcium stone for the first time, the likelihood of forming another stone is about 15% within 1 year, 40% within 5 years, and 80% within 10 years. Measures to prevent the formation of new stones vary, depending on the composition of the existing stones. Drinking large amounts of fluids—8 to 10 ten-ounce (300-milliliter) glasses a day—is recommended for prevention of all stones. People should drink enough fluid to produce more than about 2 quarts of urine per day. Other preventive measures depend somewhat on the type of stone. Calcium stones People with calcium stones may have a condition called hypercalciuria, in which excess calcium is excreted in the urine. For these people, measures that decrease the amount of calcium in the urine can help prevent formation of new stones. One such measure is a diet that is low in sodium and high in potassium. Calcium intake should be about normal—1,000 to 1,500 milligrams daily (about 2 to 3 servings of dairy per day). The risk of a new stone forming is actually higher if the diet contains too little calcium, so people should not try to eliminate calcium from their diet. However, people may need to avoid sources of excess calcium such as antacids that contain calcium. Thiazide diuretics, such as chlorthalidone or indapamide, also reduce the concentration of calcium in the urine in such people. Potassium citrate may be given to increase a low urine level of citrate, a substance that inhibits calcium stone formation. Restricting dietary animal protein may help reduce urinary calcium and the risk of stone formation in many people with calcium stones. People who have calcium stones are more likely to develop other stones if their diet has too little as well as too much calcium. A high level of oxalate in the urine, which contributes to calcium stone formation, may result from excess consumption of foods high in oxalate, such as rhubarb, spinach, cocoa, nuts, pepper, and tea, or from certain intestinal disorders (including some kinds of weight loss surgery). Calcium citrate, cholestyramine, and a diet that is low in fat and in oxalate-containing food may help to reduce urinary oxalate levels in some people. Pyridoxine (vitamin B6) decreases the amount of oxalate the body makes. In rare cases, when calcium stones result from hyperparathyroidism, sarcoidosis, vitamin D toxicity, renal tubular acidosis, or cancer, the underlying disorder must be treated. Uric acid stones Uric acid stones are almost always caused by excessive acid levels in the urine. Potassium citrate should be given to all people who have uric acid stones to make the urine alkaline and neutralize the high acid levels that cause uric acid stones. Occasionally, a low animal protein diet or allopurinol may be used to reduce uric acid levels in the urine. Maintaining a large fluid intake is also very important. Cystine stones For stones made of cystine, urinary cystine levels must be kept low by maintaining a large fluid intake and sometimes taking alpha-mercaptopropionylglycine (tiopronin) or penicillamine. Struvite stones People with recurrent struvite stones may need to take antibiotics continually to prevent urinary tract infections. Acetohydroxamic acid may also be helpful in people with struvite stones. Treatment of Urinary Tract Stones Nonsteroidal anti-inflammatory drugs (NSAIDs) or opioids as needed to relieve pain Sometimes stone removal Small stones that are not causing symptoms, blockage of the urinary tract, or an infection usually do not need to be treated and often pass on their own. Larger stones (over three sixteenths of an inch [5 mm]) and those that are closer to the kidney are less likely to pass on their own. Some drugs (tamsulosin or calcium channel blockers) may increase the likelihood of spontaneous stone passage. Pain relief The pain of renal colic may be relieved with NSAIDs. If the pain is severe, opioids are sometimes needed. Stone-passing strategies Drinking plenty of fluids or receiving large amounts of fluids intravenously has been recommended to help stones pass, but it is not clear that this approach is helpful. Alpha-adrenergic blockers (such as tamsulosin) may help the stone pass. Once a stone has passed, no other immediate treatment is needed. Stone-bypass procedures Sometimes when a blockage is severe, doctors insert a temporary tube (stent) in the ureter to bypass the obstructing stone. Doctors insert a telescopic viewing instrument (cystoscope, a kind of endoscope) into the bladder and pass the stent through the cystoscope and into the opening of the ureter. The stent is pushed up past the obstructing stone. The stent is left in place until the stone can be removed (for example, by surgery). Alternatively, doctors may drain the blockage by inserting a drainage tube through the back into the kidney (nephrostomy tube). Stone removal Often, shock wave lithotripsy can be used to break up a stone in the renal pelvis or uppermost part of the ureter that is ½ inch (1 centimeter) or less in diameter. In this procedure, shock waves directed at the body by a sound wave generator break up the stone. The pieces of stone are then passed in the urine. Sometimes, a stone is removed with grasping forceps using an endoscope (viewing tube) through a small incision in the skin, or the stone can be shattered into fragments using a probe from a lithotripsy machine and then the pieces are passed in the urine. Sometimes, a laser is used to break up the stone. When a laser is used, the procedure is called holmium laser lithotripsy. Removing a Stone With Sound Waves Kidney stones can sometimes be broken up by sound waves produced by a lithotriptor in a procedure called extracorporeal shock wave lithotripsy (SWL). After an ultrasound device or fluoroscope is used to locate the stone, the lithotriptor is placed against the back, and the sound waves are focused on the stone, shattering it. Then the person drinks fluids to flush the stone fragments out of the kidney, to be eliminated in the urine. Sometimes blood appears in the urine or the abdomen is bruised after the procedure, but serious problems are rare. Removing a Stone With Sound Waves Shock Wave Lithotripsy A ureteroscope (a small viewing telescope, a kind of endoscope) can be inserted into the urethra, through the bladder and up the ureter to remove small stones in the lower part of the ureter that require removal. In some instances, the ureteroscope can also be used with a device to break up stones into smaller pieces that can be removed with the ureteroscope or passed in the urine (a procedure called intracorporeal lithotripsy). Most commonly, holmium laser lithotripsy is used. In this procedure, a laser is used to break up the stone. Percutaneous nephrolithotomy may be used to remove some larger kidney stones. In percutaneous nephrolithotomy, doctors make a small incision in the person's back and then insert a telescopic viewing tube (called a nephroscope, a kind of endoscope) into the kidney. Doctors insert a probe through the nephroscope to break the stone into smaller pieces and then remove the pieces (nephrolithotripsy). Making the urine more alkaline (for example, with potassium citrate taken for 4 to 6 months by mouth) may sometimes gradually dissolve uric acid stones. Other types of stones cannot be dissolved this way. Surgical removal is sometimes needed for larger stones that are causing an obstruction. Endoscopic surgery is usually used to remove struvite stones. Antibiotics are not helpful in treating urinary tract infections until the infection stones are completely removed. Ureteral stenting is the placement of a soft hollow tube to help urine drain from the kidney to the bladder. A ureteral stent may be necessary for a week or two after a procedure done to remove a stone. Irritation from the stone or from the removal procedure could cause some inflammation of the ureter. The stent helps the inflammation resolve. Treatment for Kidney Stones How do health care professionals treat kidney stones? Health care professionals usually treat kidney stones based on their size, location, and what type they are. Small kidney stones may pass through your urinary tract without treatment. If you’re able to pass a kidney stone, a health care professional may ask you to catch the kidney stone in a special container. A health care professional will send the kidney stone to a lab to find out what type it is. A health care professional may advise you to drink plenty of liquids if you are able to help move a kidney stone along. The health care professional also may prescribe pain medicine. Larger kidney stones or kidney stones that block your urinary tract or cause great pain may need urgent treatment. If you are vomiting and dehydrated, you may need to go to the hospital and get fluids through an IV. Kidney stone removal A urologist can remove the kidney stone or break it into small pieces with the following treatments: Shock wave lithotripsy. The doctor can use shock wave lithotripsy NIH external link to blast the kidney stone into small pieces. The smaller pieces of the kidney stone then pass through your urinary tract. A doctor can give you anesthesia NIH external link during this outpatient procedure. Cystoscopy and ureteroscopy. During cystoscopy, the doctor uses a cystoscope to look inside the urethra and bladder to find a stone in your urethra or bladder. During ureteroscopy, the doctor uses a ureteroscope, which is longer and thinner than a cystoscope, to see detailed images of the lining of the ureters and kidneys. The doctor inserts the cystoscope or ureteroscope through the urethra to see the rest of the urinary tract. Once the stone is found, the doctor can remove it or break it into smaller pieces. The doctor performs these procedures in the hospital with anesthesia. You can typically go home the same day. Percutaneous nephrolithotomy. The doctor uses a thin viewing tool, called a nephroscope, to locate and remove the kidney stone. The doctor inserts the tool directly into your kidney through a small cut made in your back. For larger kidney stones, the doctor also may use a laser to break the kidney stones into smaller pieces. The doctor performs percutaneous nephrolithotomy NIH external link in a hospital with anesthesia. You may have to stay in the hospital for several days after the procedure. After these procedures, sometimes the urologist may leave a thin flexible tube, called a ureteral stent, in your urinary tract to help urine flow or a stone to pass. Once the kidney stone is removed, your doctor sends the kidney stone or its pieces to a lab to find out what type it is. The health care professional also may ask you to collect your urine for 24 hours after the kidney stone has passed or been removed. The health care professional can then measure how much urine you produce in a day, along with mineral levels in your urine. You are more likely to form stones if you don’t make enough urine each day or have a problem with high mineral levels. Kidney stones of varying sizes and shapes. Health care professionals usually treat kidney stones based on their size and what they are made of. How can I prevent kidney stones? To help prevent future kidney stones, you also need to know what caused your previous kidney stones. Once you know what type of kidney stone you had, a health care professional can help you make changes to your eating, diet, and nutrition to prevent future kidney stones. Drinking liquids In most cases, drinking enough liquids each day is the best way to help prevent most types of kidney stones. Drinking enough liquids keeps your urine diluted and helps flush away minerals that might form stones. Though water is best, other liquids such as citrus drinks may also help prevent kidney stones. Some studies show that citrus drinks, such as lemonade and orange juice, protect against kidney stones because they contain citrate, which stops crystals from turning into stones. Unless you have kidney failure, you should drink six to eight, 8-ounce glasses a day. If you previously had cystine stones, you may need to drink even more. Talk with a health care professional if you can’t drink the recommended amount due to other health problems, such as urinary incontinence, urinary frequency, or kidney failure. The amount of liquid you need to drink depends on the weather and your activity level. If you live, work, or exercise in hot weather, you may need more liquid to replace the fluid you lose through sweat. A health care professional may ask you to collect your urine for 24 hours to determine the amount of urine you produce a day. If the amount of urine is too low, the health care professional may advise you to increase your liquid intake. Medicines If you have had a kidney stone, a health care professional also may prescribe medicines to prevent future kidney stones. Depending on the type of kidney stone you had and what type of medicine the health care professional prescribes, you may have to take the medicine for a few weeks, several months, or longer. For example, if you had struvite stones, you may have to take an oral antibiotic for 1 to 6 weeks, or possibly longer. If you had another type of stone, you may have to take a potassium citrate tablet 1 to 3 times daily. You may have to take potassium citrate for months or even longer until a health care professional says you are no longer at risk for kidney stones. Type of kidney stone Possible medicines prescribed by your doctor Calcium Stones potassium citrate, which is used to raise the citrate and pH levels in urine diuretics, often called water pills, help rid your body of water Uric Acid Stones allopurinol, which is used to treat high levels of uric acid in the body potassium citrate Struvite Stones antibiotics, which are bacteria-fighting medications acetohydroxamic acid, a strong antibiotic, used with another long-term antibiotic medication to prevent infection Cystine Stones mercaptopropionyl glycine, an antioxidant NIH external link used for heart problems potassium citrate Talk with a health care professional about your health history prior to taking kidney stone medicines. Some kidney stone medicines have minor to serious side effects. Side effects are more likely to occur the longer you take the medicine and the higher the dose. Tell the health care professional about any side effects that occur when you take kidney stone medicine. Hyperparathyroidism surgery People with hyperparathyroidism, a condition that results in too much calcium in the blood, sometimes develop calcium stones. Treatment for hyperparathyroidism may include surgery to remove the abnormal parathyroid gland. Removing the parathyroid gland NIH external link cures hyperparathyroidism and can prevent kidney stones. Surgery sometimes causes complications, including infection. |