DESCRIPTION OF CONDITION:

Kidney stones are formed when hardened mineral deposits collect in the kidney.  This condition is termed renal stone disease.  The primary function of the kidney is to filter impurities out of the blood, adding them to the urine to pass from the body naturally.  If the waste materials in the urine do not dissolve correctly, the build-up forms kidney stones.  Many stones may pass naturally, however often times, either due to size or location, the stone will lodge itself in the kidney or in the ureter.

 SYMPTOMS:

Kidney stones are usually undetected during formation.  As the stones move into the urinary tract they are often accompanied by the following symptoms:

• Sudden and severe pain in back and side
• Frequent, burning or slow urination
• Blood in the urine
• Fever, nausea and/or vomitting

INCIDENCE AND CAUSES:

Approximately 5% of all women and 10% of men will have a kidney stone once in their lifetime.  Kidney stones are especially common in dry, hot climates and caucasians are more prone to the disease than in people of African descent.  Kidney stones are usually first detected in people between the ages of 20 and 45, but will sometimes develop in children. 

More than 70% of kidney stones contain calcium.  Calcium oxalate stones are most common. They often develop due to insufficient fluid intake preventing the body from flushing out or dissolving impurities. Other types of stones include calcium phosphate, struvite (also know as magnesium ammonium phosphate), uric acid and cystine stones.

The most common causes of kidney stones are dehydration and poor nutrition.  Certain medications such as antacids and protein supplements have also been linked to kidney stones.  Cystine stones are linked to heredity and although rare have been seen in children. 

ANATOMY:

The urinary tract consists of the kidneys, ureter, bladder and urethra.  The main function of the kidneys is to filter out impurities and add them to the urine.  Inside the kidneys, urine is collected in the renal pelvis and the calyxes (collecting structures).  The urine then trickles down the ureter into the bladder.  The undissolved waste materials remain in the kidneys.  Over time the waste materials can build-up creating kidney stones.

The size of a kidney stone may vary from a few millimeters to several centimeters.  Many stones pass naturally through urination however some stones, due to their size, will become lodged in either the kidney or the ureter.  Stones lodged in the ureter are termed ureteral stones.

PROCEDURE:

Extracorporeal Shock Wave Lithotripsy (ESWL) is the most frequently used treatment method of kidney stones.  Prior to treatment, the stone is located by the use of X-ray or ultrasound.  During the procedure, a light anesthetic may be given to help reduce any discomfort.  The treatment delivers high-energy shock waves to a precise location in the body to crush the stones into small fragments, at the same time avoiding damage to surrounding soft tissue.  The stone fragments then pass naturally through urination.  The procedure takes approximately 30 to 60 minutes, and can be performed in a hospital or out-patient center.

POST PROCEDURE PROTOCOL:

Most patients only experience minimal side effects after the procedure.  Side effects may include mild discomfort in the abdominal region, along with redness or bruising at the treatment site, and blood in the urine.  Patients can return to a normal routine within twenty-four hours of the treatment. 

ALTERNATIVE TREATMENT OPTIONS:

Open surgical treatment – With the invention of ESWL, open surgical procedures are rarely performed on the kidney.  There are, however, specific indications that often make open surgery necessary. These include:

• Failure of less invasive treatments due to size, composition and location of the stone
• Certain anatomic configurations of the urinary tract

Minimally Invasive Treatments – Ureteroscopy (URS) can be performed to remove stones located in the lower part of the ureter.  During this procedure, an ureteroscope is inserted through the urethra to gain access to the stone.  Once the stone is located, it is either removed by means of a small basket “grabbing” the stone and pulling it out, or by means of laser therapy, which breaks up the stone, allowing patients to pass the fragments in their urine.  Due to the nature of these procedures, down time can be several days, with greater pain than other non-invasive alternatives. 

Percutaneous Nephrolithotomy (PCNL) – This method is often used on kidney stones larger than 2 centimeters in size or for hard stones. General anesthesia is required.  A small incision is made in the back and a telescope (called nephroscope) is passed directly into the kidney. Direct fragmentation of the stone is performed using an ultrasonic, electrohydraulic, or laser device through the nephroscope under direct vision. This treatment can also be performed using the Dornier Medilas H20.

Conservative treatment – Diet, hydration, medications or a combination of these treatments may assist to pass the stone naturally. The conservative treatment is only successful for stones smaller than 5 mm in diameter. The effectiveness of medications depends on the composition of the stone.