KIDNEY STONES
Walter. O'Brien, M. D., Urologist

Kidney stones are a common condition that urologists take care of all the time. To understand where kidney stones come from, it's first necessary to understand how the urinary system works. Urine is made in the kidneys. The kidneys, which sit high in the back under the rib cage, filter the blood for excess waste products and fluid to form the urine. Once made in the kidneys, the urine travels down a tube on each side called the ureter until it reaches the bladder. The bladder's job is to store the urine until it is full and then it empties urine to the outside through the urethra.

Stones form in the kidney typically when there is an excess of calcium, oxalate, or uric acid. When there is an excess of one of these compounds in the urine, they do not stay, dissolved. Instead they begin to crystallize. The crystals can then join together to form a stone. An excess concentration can occur when there is too much of the material to be handled by the kidney (as can occur if the diet is too rich in these substances); or if there is too little fluid in the urine (as can occur when fluid intake is inadequate).

Stones cause trouble as they begin to move down the ureter. A stone can block the ureter causing back pressure on the kidney which results in pain. The pain can be extremely severe at times and may trigger nausea and vomiting. As the stone moves down the ureter, it may only block the tube intermittently, which is why the pain can come and go. Once the stone reaches the bladder, the hard work is done and it can then pass to the outside easily through the urethra. The urethra is about 4 times larger in size than the ureter. Many patients urinate the stone to the outside without being aware that they have done so.

A variety of treatment options are used for managing stones. If the stone is small enough, a "trial of labor" is recommended, which means the patient tries to pass the stone. Increased fluids are recommended in an effort to "push" the stone through. Pain pills are made available to help control the pain that can accompany stone passage. When pain begins, it is often helpful to take the pain medication as prescribed and to get into a tub of hot water or a hot shower for 15-20 minutes. This provides temporary relief until the pain pills start to work. If the pain pills do not work, then it's best to go to the hospital emergency room to get a pain shot and have the doctors there contact us.

The urine should be strained to catch the stone so it can be analyzed to determine the type of stone. Based on the results of the stone analysis, a change in diet and fluid intake may be recommended.

During a "trial of labor," regular follow up exams and x-rays are carried out as needed to monitor the progress of the stone.

Surgical intervention for a stone may be indicated for a variety of reasons, some of which can include stone size or location, the degree of blockage to the kidney, coexistent infection, fever, failure to pass the stone after a "trial of labor" and repeated episodes of pain. In the past the standard way to remove stones was with an incision. Currently, most stones can be removed with newer techniques.

If a stone is in the kidney or upper ureter, a procedure called lithotripsy or ESWL is used. This technique, often done as an outpatient procedure under sedation or general anesthesia, uses shock waves to fragment the stone into pieces. These smaller pieces can then pass more easily through the urinary system.

When the stone is in the lower ureter a technique called ureteroscopy can be used. In this procedure, done under anesthesia, a fiberoptic instrument is passed through the urethra and bladder into the ureter up to the stone. The stone can be grabbed with a basket and removed. If the stone is too large to pull out, a laser can be used to fragment the stone into smaller pieces which can then be removed.

With any of these procedures, a device called a stent may be used. The stent is a hollow tube like a straw used to keep the ureter open. It is placed in the ureter using a fiberoptic instrument. One end of the stent curls in the kidney, and the other end curls in the bladder. Stents are very effective at keeping the ureter open but they can cause annoying symptoms for some patients. The stent can irritate the bladder and cause urinary symptoms that can include frequency, urgency (the need to go right away), uncomfortable urination and blood in the urine. Pain or pressure in the back with urination can occur as well.

After the stent has served its purpose, usually after a few days or even a few weeks, it needs to be removed. This typically can be done in the office but occasionally may be carried out with sedation at the hospital as an outpatient.

The development of a kidney stone is often alarming for many patients. However, with modern techniques it is a problem that can be readily addressed and cured.