Description of Condition:

One of the tasks of the kidney is to filter out impurities and deposit them into the urine. These impurities usually dissolve in the urine and are flushed out naturally. When these impurities do not dissolve completely the particles remain in the kidney.  Small crystals form and stick together creating kidney stones.  This condition is termed renal stone disease.

Laser lithotripsy is the fragmentation of calculi, known as kidney stones, using the holmium laser. Calculi may appear in the kidney, ureter, bladder or urethra. The laser light is transferred to the stone through a flexible lightguide through the urethra. The high absorption of the holmium laser light by the calculus leads to the fragmentation of the stone regardless of its chemical composition. Endoscopic imaging and controlled laser pulses ensure safe contact between the fiber tip and stone. Lithotripsy using the holmium laser is characterized by a high success rate and low complication rate for all types of stones.

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:

About 5 % of all women and 10 % of men have a kidney stone once in a life time. Kidney stones usually appear in people between the ages of 20 – 45, and occasionally develop in children.  After the age of 50 the incidence rate declines.  Kidney stones are especially common in dry, hot countries and are seen more often in Caucasians than people of African descent.

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, ureters, 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:

If a patient show symptoms of a urinary stone, the physician will diagnose the problem using either x-ray or ultrasound imaging.  Lithotripsy is a technique for breaking up stones. There are several ways of performing lithotripsy. The doctor will discuss the best method based on the size and location of the stone as well as patient history. The most common treatment for urinary stones is extracorporeal shock wave lithotripsy (ESWL), however not all stones can be treated using this method. The Dornier Medilas H20, a holmium: YAG laser, is a good alternative for very large or difficult to reach stones.

Laser lithotripsy is performed under general anesthesia. To monitor the procedure an endoscope is used, which has a camera on the end of a long, flexible tube.  The endoscope is inserted into the body through the urinary tract and advanced to the location of the stone. The light energy of the laser is transported through a light guide to the stone.  The light guide enters the body through a tunnel in the endoscope. Stone fragmentation occurs when pulses of intense laser light from the Dornier Medilas H20 are applied. The stone particles then flush out naturally.

POST PROCEDURE PROTOCOL:

Following the procedure a small amount of blood may be seen in the urine. The patient may also experience the urge to urinate.  This is a possible side effect from bladder and urethra irritation caused by the introduction of the endoscope into the urinary tract.  This urge usually disappears in a few days.

Overnight stay in the hospital is typically not required.

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

• Extracorporeal Shock Wave Lithotripsy (ESWL) – A minimally invasive treatment in which shock waves are generated outside of the body and focused on the urinary stone using a lithotripter. The shock waves break the kidney stone into small pieces that are passed naturally during urination.

• 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.

• Endoscopic treatment - The endoscopic treatment, as described using laser lithotripsy, can also be performed with a specialized basket removing the stone completely.  The advantage of Holmium laser lithotripsy over other endoscopic treatments is less stone movement and less bleeding during treatment.