DESCRIPTION:
Laser lithotripsy is the fragmentation of calculi using the Holmium laser. The high absorption of the Holmium laser light (wavelength: 2.1 µm in the infrared) by the calculus leads to the ablation of the calculus material regardless of its chemical composition. Endoscopic imaging and controlled laser pulses ensure safe contact between the fiber tip and calculus. Thin fibers with a core diameter of 200 µm allow thinner endoscopes to be used to advance to the renal calyces. Lithotripsy using the holmium laser is characterized by a high success rate and low complication rate for all types of calculi.
SYMPTOMS:
Kidney stones are usually undetected during formation. As the stone moves into the urinary tract they are often accompanied by the following symptoms:
- Renal colic
- Frequent, burning or slow urination
- Blood in the urine
- Fever, nausea and/or vomiting
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.
When the urine becomes too concentrated with impurities, small crystals may form and develop into stones. Calcium oxalate stones are most common. They often develop due to insufficient fluid intake. Other types of stones include calcium phosphate, struvite, uric acid and cystine stones.
The most common causes of calculi are dehydration and poor nutrition. Certain medications such as antacids and protein supplements have also been linked to calculi formation. Cystine stones are linked to heredity and although rare, have been seen in children.
Anatomy:
Urinary system, including kidneys, ureter and bladder
PATIENT SELECTION:
Contraindications to laser lithotripsy include bleeding tendencies, active urethritis, or patients who are not suitable for general anesthesia.
PROCEDURE:
During the consultation of a patient showing symptoms of urinary stones the patient’s medical history, physical examination, laboratory evaluation and imaging tests will be tools for diagnosing. Imaging tests, such as x-ray imaging or ultrasound imaging determine the location of the calculi.
The most common treatment for urinary stones, extracorporeal shock wave lithotripsy (ESWL) is not ideal for all stones. 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. The light energy of the laser is transported through a flexible light guide to the stone. For ensuring a safe procedure the laser fiber is observed with an ureterorenoscope. The fiber tip must be in contact with the stone during the firing of the laser. The stone breaking mechanism of laser lithotripsy is a thermal one. The stone fragments when pulses of intense laser light from the Dornier Medilas H20 are applied.
   
Based upon the principle that Holmium laser energy is strongly abosrbed by water, the short laser pulses create a shockwave that causes fragmentation of both ureteral and intrarenal stones. Due to the flexibility and control of the system, different treatment techniquest can be applied depending upon the location and shape of the stone. For example, smaller stones can be fragmented directly, whereas with larger concrements, holes are first made in the center, after which the edges can then be fragmented. Finally, the stone residues can be flushed out utilizing the endoscopes rinsing fluid.
POST PROCEDURE PROTOCOL:
After the procedure maybe a small amount of blood may be seen in the urine. The patient may also experience the urge to urinate caused by irritation in the bladder and urethra from the ureterorenoscope.
Overnight stay in the hospital is typically not required.
ALTERNATIVE TREATMENT OPTIONS:
Open surgical treatment – With the invention of ESWL, open surgical procedures on the kidney are rare. There are, however, specific indications, which make open surgery necessary. These include:
- Failure less invasive treatments due to size, composition and location of the stone
- Certain anatomic abnormalities 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 calculi into small pieces that are passed out of the body naturally during urination.
Percutaneous Nephrolithotomy (PCNL) – This method is often used for calculi larger than 2 centimeters in size or for hard stones. General anesthesia is required. A small incision is made in the back and a 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 the natural passing of the calculi. The conservative treatment is only successful for stones smaller than 5 mm in diameter. The effectiveness of medications is dependent on the composition of the stone.
Endoscopic treatment - The endoscopic treatment, as described using laser lithotripsy, can also be performed using a specialized basket to remove the stone completely. The advantage of Holmium laser lithotripsy over other endoscopic treatments is decreased stone movement and decreased bleeding during treatment.
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