Shock Wave Technique Treats Small Kidney Stones

Nov. 19, 2010 -- A shock wave technique was effective in treating single kidney stones less than 1 centimeter in size and may be a safe and noninvasive alternative to the standard surgical therapy, a study shows.

Surgeons from University Frederico II in Naples, Italy, studied 273 patients between March 2006 and March 2009 who had single stones in the section of the ureter closest to the bladder; the stones ranged in size from a half centimeter to 1.5 centimeters. Patients were randomly assigned to receive either ureteroscopy or a shock wave technique called extracorporeal shock wave lithotripsy (ESWL).

Ureteroscopy is an invasive surgical procedure that does not involve any incisions, but does involve inserting a catheter into the urethra, then passing it through the bladder and the ureter to remove the stone.

ESWL involves sending acoustic shock waves to the body to break up a single kidney stone into smaller pieces so it can be passed through the urethra on its own.

Shock Wave Technique vs. Surgery

Ninety-eight percent of the ESWL treatments were performed on an outpatient basis, did not require anesthesia or sedation, and lasted an average of about a half hour. Ninety-six percent of the ureteroscopy procedures were performed on an inpatient basis. Sixty-six percent of the group needed local anesthesia, 22% needed general anesthesia, and 12% had IV anesthesia. The surgery took about a half-hour, on average. The mean age for both treatment groups was about 50.

The study results show that:

• 93% of the ESWL group was stone-free within three months of the procedure, compared with 95% of the ureteroscopy group.
• Just one ESWL session was sufficient to remove stones for 55% of the group; 31% needed two sessions and 13% needed three sessions. All EWSL failures, seen in 7% of the group, were successfully treated with ureteroscopy.
• In the ureteroscopy group there was a retreatment rate of 8% and a need for a supplementary intraoperative procedure in 19%.
• Both groups endured side effects. In the ESWL group, 15% experienced complications;  two-thirds of this group with complications needed a stent placed in the ureter after developing a kidney infection. Stent placement was required in 17% of the ureteroscopy group.
• More than 19% of the ureteroscopy group experienced complications, including one participant who had a small perforation of the ureter. 
• In participants who had stones 1 centimeter or less, those treated with ESWL had fewer complications and less need for retreatment or supplementary treatment than those treated with ureteroscopy.

“These results clearly indicate that ESWL should be the first choice for patients with stones of 1 centimeter and under and ureteroscopy should be the first choice for patients exceeding 1 centimeter,” the researchers say in a news release.

The results are reported in the December issue of the urology journal BJUI.