extracorporeal shock-wave lithotripsy


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lithotripsy

 [lith´o-trip″se]
the crushing of calculi in the bladder, urethra, kidney, or gallbladder.
electrohydraulic lithotripsy a method used for large upper urinary tract calculi: a high-capacity condenser creates a high-voltage spark between two electrodes at the tip of a probe; in a fluid-filled organ this creates a hydraulic shock wave that can be directed toward a calculus, causing it to cavitate and fragment.
extracorporeal shock-wave lithotripsy (ESWL) a noninvasive fragmentation of kidney stones or gallstones with shock waves generated outside the body. It requires no incisions, catheters, or nephroscopes. The technique is based on the principle that shock waves are not destructive until they reach a surface in which there is a change in acoustical impedance, which is a form of resistance to the passage of sound waves. The impedance of calculi is different from that of water, bone, and soft tissue; therefore, tissue through which the wave travels as well as tissues surrounding the stone are not harmed.

For kidney stones, ESWL shatters the calculi into particles small enough to be passed in the urine. The procedure takes no longer than one to two hours, permits a shorter hospital stay, and allows the patient to return to normal life without delay.

ESWL is not appropriate for every patient with kidney stones. Body structure may prohibit proper positioning in the tank of water in which the patient must be submerged. Other contraindications include calcium deposits in the arteries, obstruction to urine flow, which is depended upon to flush out the fragments, and exaggerated spinal curvature, which interferes with visualization on x-ray. Stones that are not radiopaque cannot be treated by ESWL unless a radiopaque contrast medium is used because otherwise they cannot be seen and the shock waves cannot be properly focused on them. Very large stones (over one and a quarter inches in diameter) are not amenable to ESWL because they require more energy than the equipment can generate to break them into pieces small enough to travel through the urinary tract.

Complications such as obstruction to urine flow, bleeding, infection, and pain are less for ESWL than for other modes of therapy. The most formidable obstacle to widespread use of ESWL is the cost of the equipment.

For treatment of gallstones, the lithotriptor is used in combination with an ultrasound probe. The probe locates the calculi and the lithotriptor is fired. The fragments of gallstone traverse the biliary tract and are excreted via the intestines.
Extracorporeal shock-wave lithotripsy. Electrically generated shock waves can fracture renal calculi. From Polaski and Tatro, 1996.
percutaneous ultrasonic lithotripsy (PUL) surgical removal of kidney stones via an incision and insertion of a nephroscope into the portion of the kidney where the stone is lodged. An attempt is first made to remove the calculus through the endoscope by basket or forceps. If this is not successful, an ultrasonic lithotrite that sends out high-frequency sound waves is used to break up the stone. A continuous saline irrigation flushes out the particles, which are removed by suction. The drainage is filtered to trap the particles so that they can be sent to the laboratory for analysis.

Advantages of PUL over conventional surgical procedures for removal of kidney stones are fewer complications, a surgical incision less than 1 to 2 cm long as compared to one 20 cm long, shorter hospital stay, and more rapid recovery.
Patient Care. Preoperative care is fairly routine. The procedure usually is done in the radiology department and may be done in one or two stages. In the first stage the incision is made under local anesthesia and the nephrostomy catheter is inserted. In the second stage a general or epidural anesthetic is used and the ultrasonic lithotrite or “wand” is passed through the nephroscope. Ultrasonic waves of approximately 25,000 hertz are thus focused on the stone, breaking up its crystalline structure.

After surgery the vital signs are monitored to detect evidence of bleeding or infection. Some bright red blood in the urine passing through the nephrostomy can be expected for one to three days, but the amount of blood should gradually diminish. As bleeding subsides the urine becomes smoky and tinged with old blood. The kidney is a highly vascular organ and postoperative hemorrhage is always a threat.

If the patient has either a Foley catheter or a ureteral catheter or both remaining in place after surgery, they must be kept open and draining. Irrigations, if ordered, are done gently to avoid excessive bleeding. A decrease in drainage and flank pain may indicate obstruction in the urinary tract. Other complications to be watched for include retroperitoneal bleeding, infection, delayed allergic reaction, and pneumothorax or hemothorax.

If the patient goes home with the catheter in place, instruction in self-care is necessary. The patient and family will need to know how to care for the incision site and the urine collection device. They should be taught how to note and record urine volume and evaluate its color and to report to the physician any leakage of urine from the incision site that persists after four days. They also will need to report any symptoms of infection, development of pain, or bright red hematuria. The importance of taking antibiotics precisely as prescribed is stressed. Antibiotic therapy is usually continued for two weeks after surgery. If no complications develop, the patient is able to return to normal daily activities within a week after drainage stops.

extracorporeal shock-wave lithotripsy (ESWL)

Etymology: L, extra, outside, corpus, body; Fr, choc + AS, wafian + Gk, lithos, stone, tribein, to wear away
use of vibrations of powerful sound waves to break up calculi in the urinary tract or gallbladder. Also called shock wave lithotripsy.

extracorporeal shock-wave lithotripsy

ESWL, lithotripsy, shock-wave lithotripsy Nephrology A non-surgical, non-invasive method for dissolving renal–chenodeoxycholic and ursodeoxycholic acids, and biliary tract calculi; the Pts lie prone and partially immersed in a large bathtub-like vat; shock waves are generated extracorporally by high-energy underwater spark discharge focused on the Pt's ventral aspect by a reflector
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EXTRACORPOREAL SHOCK WAVE LITHOTRIPSY: Shock waves are transmitted through water to break up gallstones. A. Position for stones in gallbladder. Patient is lying on a fluid-filled bag; B. Position for stones in common bile duct. Patient is in a water bath.
Enlarge picture
EXTRACORPOREAL SHOCK WAVE LITHOTRIPSY: Shock waves are transmitted through water to break up gallstones. A. Position for stones in gallbladder. Patient is lying on a fluid-filled bag; B. Position for stones in common bile duct. Patient is in a water bath.

extracorporeal shock-wave lithotripsy

Abbreviation: ESWL
The fragmentation of kidney stones with an extracorporeal shock-wave lithotriptor.
See: illustration
See also: lithotripsy

Extracorporeal shock-wave lithotripsy (ESWL)

This is a technique that uses high-pressure waves similar to sound waves that can be "focused" on a very small area, thereby fracturing small solid objects such as gallstones, kidney stones, etc. The small fragments can pass more easily and harmlessly into the intestine or can be dissolved with medications.
Mentioned in: Cholangitis
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