Extracorporeal shock wave lithotripsy (ESWL) for gallstones is a non-invasive procedure for disintegrating gallstones. High-intensity shock waves (500–1500 shocks over 30–120 minutes) are focused sonographically on the gallstones. Originally, ESWL was used in isolation for treatment of gallstones, but subsequently patients were additionally treated with ursodiol, a naturally occurring biliary acid that functions to further dissolve the fragmented stones. Patients are typically treated with ursodiol for a week before the procedure and after the procedure until stone clearance has been documented or up until 20 months.

In 2000, Medstone, a manufacturer of an ESWL device, received approval by the U.S. Food and Drug Administration (FDA) for ESWL in conjunction with urosdiol as a treatment of “symptomatic, solitary, radiolucent non-calcified gallstones (between 4 and 20 mm in maximum diameter) in adult patients for whom surgical removal of the gallbladder is medically contraindicated and in symptomatic high-risk patients who have actively refused surgery.”

Extracorporeal shock wave lithotripsy (ESWL) for gallstones, in conjunction with ursodiol therapy, may be considered medically necessary only in that small subset of patients with symptomatic non-calcified single gallstones measuring 20 mm or less AND who are either not considered candidates for either open or laparoscopic cholecystectomy due to comorbidities, or who actively refuse a surgical option.

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The FDA approved use of biliary lithotripsy includes the administration of ursodiol 2 weeks prior to the procedure and continues up to 20 months after or until a stone-free state is achieved. As a self-administered drug, pharmacy benefits may apply to coverage eligibility of ursodiol.

Enthusiasm for ESWL treatment of gallstones was initially prompted by successful ESWL treatment of kidney stones. Fragmented renal stones could be flushed out relatively easily through the urinary flow. However, in the dependent gallbladder, the fragmented gallstones were often retained and could lead to recurrent biliary colic. In the early 1990s interest in ESWL of gallstones waned as laparoscopic cholecystectomy emerged as the treatment of choice for symptomatic cholelithiasis. Research on ESWL treatment of gallstones refocused on its use as an adjunct to ursodiol treatment. In this setting, ESWL was used as a treatment to increase the effectiveness of ursodiol therapy by fragmenting the stones thus increasing their surface area. (1) In fact the clinical studies presented to the FDA as part of the approval process focused on the ability of ESWL to enhance the effectiveness of ursodiol alone. The labeled indication for ESWL for gallstones suggests that the drug be given 2 weeks prior to ESWL and then continued up to 20 months after ESWL or until a stone-free state is achieved.

The FDA approval was based on several different studies performed in the 1980s. The data from these studies were reanalyzed to permit a comparison between the outcomes of ursodiol treatment alone and ursodiol treatment combined with ESWL treatment. This complex statistical analysis is difficult to follow in the available FDA advisory committee minutes. (2) However, the data suggest that the clearance rate of gallstones was 60% better in those receiving the combined therapy compared to those receiving ursodiol alone. The best results were seen in those with a single non-calcified gallstone measuring less than 20 mm in diameter. However, it is clear that cholecystectomy still represents the treatment of choice, due to the prompt resolution of symptoms in appropriately selected patients and the absence of stone recurrence, which may recur at a rate of 10% per year in the absence of cholecystectomy. Approximately 500,000 patients per year undergo cholecystectomy. Of these, perhaps 150,000 would be considered candidates on the basis of stone number and size alone. Only a small percentage of these patients would not be considered surgical candidates.

References:

1. Howard DE, Fromm H. Nonsurgical management of gallstone disease. Gastroenterol Clin North Am 1999; 28(1):133-44.
2. FDA Advisory Committee Minutes at: www.fda.gov/ohrms/dockets/ac/98/transcpt/3410t1.rtf.

Extracorporeal shock wave lithotripsy for gallstones
Gallstones, extracorporeal shock wave lithotripsy
Lithotripsy, extracorporeal shock wave, for gallstones