ESWL shows efficacy in patients with SSD >13 cm

December 20, 2013

Ureteric calculi at a skin-to-stone distance (SSD) of over 13 cm can be successfully managed using extracorporeal shock wave lithotripsy, British researchers report.

Edinburgh, United Kingdom-Ureteric calculi at a skin-to-stone distance (SSD) of over 13 cm can be successfully managed using extracorporeal shock wave lithotripsy, British researchers report.

Conventional wisdom holds that ESWL is not viable for patients with an SSD greater than 12 cm, but with the increasing prevalence of obesity, patients are only getting larger, lead author Sara Ramsey, MD, told Urology Times.

“We bought a machine that said it would treat up to 17 cm, which we pretty much took with a pinch of salt. But increasingly, our radiographers were saying, ‘Look, I think we can hit this. I think we can treat this,’ ” explained Dr. Ramsey, a stone fellow at the Scottish Lithotripter Centre in Edinburgh, UK, who worked on the study with Simon Phipps, MD, and colleagues.

Dr. Ramsey and her colleagues then decided to put their lithotripter, the Sonolith i-sys (EDAP TMS, Vaulx-en-Velin, France), to the test. They selected 98 patients with ureteric stones to undergo ESWL. The majority of patients were male, with a mean age of 51 years, mean upper ureteric stone size of 8 mm, and mean SSD of 14 cm.

The patients were treated on an outpatient basis at a frequency of 2 Hz. Success was defined as complete clearance of stone fragments; failure was defined as persistence of stone fragments beyond 3 months or the need for ureteroscopy. The authors assessed outcomes on an intention-to-treat analysis.

67% of patients stone free after 1 session

After a single session of ESWL, 66 patients (67%) were stone free, Dr. Ramsey reported at the 2013 AUA annual meeting in San Diego. Twenty-four patients underwent an additional session, after which the overall stone-free rate rose to 80%. Twelve patients proceeded to ureteroscopy. Two patients failed to tolerate treatment. The authors observed a stone-free rate of 69% for lower and mid-ureteric stones and 85% for upper ureteric stones.

“We were actually surprised by how well our upper ureteric stone [patients] do,” Dr. Ramsey said.

Dr. Ramsey said that based on her group’s findings, she would recommend that clinicians attempt ESWL at a heightened SSD.

“Anybody looking to upgrade their lithotripter should think very hard about getting one with a focal length that extends to 17 cm. What you really want is to be able to treat the maximum number of patients that are suitable, rather than being cut off,” Dr. Ramsey told Urology Times.

Dr. Ramsey has received a travel grant from EDAP TMS.UT

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