Urinary Stone Disease

Kidney stones form in the interior of the kidney wall where urine collects prior to flowing through the ureters to reach the bladder. The kidneys produce urine as they process waste and extra water out of the blood and maintain the body’s balance of water, salts, acid, and minerals. Kidney stones form when substances which normally dissolve in the urine become concentrated and form crystals. They begin as small crystals that increase in size as more minerals or molecules attach to one another. There are several types of kidney stones.

Evaluation

Kidney stones are most commonly diagnosed when the stone breaks away from the wall of the collecting system and, following the flow of urine, lodges in the ureter. The lodged stone causes blockage of urine flow and increased pressure in the collecting system. The stretching of the ureter and the collecting system causes excruciating pain which prompts most patients to seek emergency treatment. The pain is typically felt in the flank (the back) but may "radiate" to the lower abdomen or the groin. Other symptoms may include blood in the urine (sometimes visible to the naked eye known as “gross hematuria” and other times only visible by microscopic examination of the urine known as "microhematuria"), nausea/vomiting, persistent urinary tract infections and urinary urgency.

Besides a complete review of symptoms and a medical/ surgical history, evaluation will include examination of the urine to detect blood or evidence of infection, and a blood test to determine baseline kidney function. Ultimately, radiologic imaging of the urinary system must be performed to provide definitive proof of stones in the urinary system. This process is most commonly done with a CT scan without x-ray dye or a simple x-ray of the abdomen. Rarely, an IVP (intravenous pyelogram) will assist in the diagnosis of a kidney stone.

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Treatment

Kidney stones which are too large to pass on their own, which are causing pain that cannot be controlled with oral medication or are associated with infection, fever or vomiting will require treatment. Additionally, patients with poor kidney function, a single kidney or a complete blockage of urine will also need treatment. There are several treatments available for kidney stones, and patients should be counseled to select the treatment best suited for their individual condition.

Extracorporeal Shock-Wave Lithotripsy (ESWL):

ESWL, developed in the mid-1980’s, revolutionized treatment of kidney stones. The process consists of using a series of shock waves aimed at the stone to break it up into small fragments. The shock waves are generated by a lithotripter, and are focused precisely by x-ray to achieve maximum intensity at the stone causing the stone to fracture into small particles that can pass out of the kidney. ESWL is the only non-invasive treatment for kidney stones. It requires no incision and is usually performed as an outpatient procedure under general anesthesia. For stones that are larger than one inch in diameter, a stent (tube) may be inserted in the kidney to reduce the probability of blockage of the ureter by stone fragments as they pass.

Advantages: The ESWL procedure offers a non-invasive technique of pulverizing stones into fragments that can pass through the ureter. Depending upon the size of the stone and its position in the kidney, successful fragmentation of the stones in one treatment session is expected in 50-70% of patients. ESWL works best for patients with small stones that can easily be seen by x-ray.

Disadvantages: Use of ESWL in patients with large stone burden may require more than one treatment. Patients with stones located in the lower peripheral collecting system have an increased probability of failure. In case of stone fragments causing obstruction, ureteroscopy may be necessary to remove stone fragments lodged in the ureter. Since ESWL does not eliminate the stone material at the time of treatment, it is not the proper treatment for patients who require a complete and immediate removal of all stone fragments. Additionally, some stones such as cystine and certain types of calcium stones do not fragment well with ESWL.

Ureteroscopy

Ureteroscopy entails the passing of a small telescope through the bladder and up the ureter. Once a stone is encountered, it can be fractured using laser energy delivered via a small glass fiber. Fragments of stone are removed by grasping with a stone “basket”. Typically, a soft ureteral stent is left in the ureter to prevent blockage by stone fragments or swelling of the ureteral tissues. This stent is removed in the office under local anesthesia 2 weeks after the procedure. Depending upon the circumstance, patients may go home the same day or may be admitted overnight to ensure pain is controlled by oral analgesics.

Advantages: Ureteroscopy can treat stones in the ureter and in the kidney, including stones that are not visible by x-ray imaging. Ureteroscopy can be used for patients who are not candidates for other treatments such as those who must take blood thinners, the morbidly obese, and women who are pregnant.

Disadvantages: Removal of large stones in the kidney may not be possible using ureteroscopy. Stone fragments may be washed back into the kidney during the procedure and require re-treatment using other techniques. There is a small risk of scarring of the ureter leading to stricture.

Percutaneous nephrostolithotomy (PCNL) or (PERC)

PCNL entails the placement of a hollow tube into the kidney through a small (1 inch) incision in the back for removal of larger stones that cannot be treated by other means. This access to the kidney allows the use of an ultrasonic lithotriptor- a rigid instrument that vibrates and pulverizes the stone into granules that are suctioned out of the kidney through the center channel of the instrument. Larger fragments can be removed through the access tube using graspers.

Advantages: PCNL offers the best treatment for removal of large stones, including infected staghorn stones, to achieve a stone-free kidney after a single procedure. Occasionally, a second procedure may be indicated in patients whose large stone burden can not be removed in one sitting. Determination of successful stone removal requires a CT scan without dye to identify any stone fragments that may be too large to pass through the ureter. In most cases, the nephrostomy tube that is inserted to drain the kidney will be removed the following day.

Disadvantages: PCNL is a minimally invasive procedure, but potential complications include bleeding and renal injury that may require repair or removal of the kidney. The patient may return home on the day of surgery, but, in most cases, will stay overnight to ensure proper pain management with oral analgesics.

Open surgery

Open surgery for kidney or ureteral stones is rarely required. Patients who have undergone complicated urinary tract reconstruction, patients with congenital malformations of the urinary tract, or patients with large staghorn stones may not be candidates for minimally invasive surgery techniques.

Combination therapy

Combination therapy, also known as sandwich therapy (for example, combining PCNL with ESWL) may be used in patients with especially large stones that are not successfully removed by any one technique.

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The University of Cincinnati Urology Division is one of the leading urology programs, not just in Cincinnati, but in the U.S. UC Urology provides quality health care using the most advanced technology and state-of-the-art diagnostic treatments. Many of our urologists are recognized in multiple national and local "Best Doctors" and "Top Doctors" listings. We provide minimally invasive surgical treatments which include laparoscopic, robot-assisted laparoscopic and endourologic procedures as well as comprehensive care for all urologic conditions.