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BCM - Baylor College of Medicine

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Urology

Stone Disease (Kidney Stones)

Stone disease, one of the most painful of urologic disorders, is not a product of modern life. In fact, scientists have found evidence of kidney stones in a 7,000-year-old Egyptian mummy.

A kidney stone is a hard mass developed from crystals that separate from the urine and build up on the inner surfaces of the kidney. Normally, urine contains chemicals that prevent the crystals from forming.

Kidney stones may contain various combinations of chemicals. The most commonly found stones are calcium stones. There are also uric-acid, cystine and struvite stones.

Fortunately, most kidney stones pass out of the body without any intervention by a physician. Stones that cause lasting symptoms or other complications may be treated in various ways, most of which do not involve major surgery. Moreover, research has led to a better understanding of the many factors that promote stone formation, so there is improved opportunity for preventing their occurrence.

Symptoms

The first symptom of a kidney stone usually is extreme pain. The discomfort often begins suddenly when a stone moves in the urinary tract, causing irritation or blockage. Typically, a person feels a sharp, cramping pain in the back and side in the area of the kidney or in the lower abdomen. Sometimes nausea and vomiting occur. Later, pain may spread to the groin. As the stone grows or moves, blood may appear in the urine. As the stone moves down the ureter closer to the bladder, a feeling to urinate may occur more often or there may be a burning sensation during urination. If fever and chills accompany any of these symptoms, an infection may be present.

Diagnosis

Sometimes "silent" stones that do not cause symptoms are found on x-rays taken during a general health exam. These stones probably would pass unnoticed.

More often kidney stones are found on an x-ray or sonogram taken when someone complains of blood in the urine or sudden pain.

Sometimes the physician may scan the urinary system using a special x-ray test called an IVP (intravenous pyelogram). Results of these tests aid in the choice of the proper treatment.

Treatment Options

Most kidney stones can pass through the urinary system with plenty of water (2-3 quarts a day) to help move the stone along.

Medical therapy and prevention. For people who are at risk of forming stones or who have a history of stone disease, there are medications and life style changes that can reduce the chances of stone formation. Certain medications can help to prevent calcium and uric acid stones by controlling the amount of acid or alkali in the urine. Keeping the urine free of bacteria that can cause infection is important for preventing recurrence of struvite stones.

Extracorporeal shock-wave lithotripsy. Extracorporeal shock-wave lithotripsy is the most frequently used procedure for treatment of kidney stones. In ESWL, shock waves that are created outside of the body travel through the skin and body tissues until they hit the dense stones. The stones break down into sand-like particles and are easily passed through the urinary tract in the urine.

Surgical treatment. Surgery usually is not necessary and is generally reserved as an option to be used when other approaches have failed.

Sometimes a procedure called percutaneous nephrolithotomy is used to remove a stone that is very large or in a location not accessible to ESWL. In this procedure a tiny incision in the back creates a tunnel directly into the kidney so the stone can broken up into small pieces, if necessary, and lifted out.

For kidney stones that have lodged in the ureters a ureteroscope may be used. No incision is made in this procedure. Instead, the surgeon passes a small fiberoptic instrument through the urethra and bladder into the ureter. The stones are located and either removed with a cage-like device or shattered with a special instrument that produces a form of shock wave.