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Game-changing technology pulverizes kidney stones

The super-pulsed thulium fiber laser can reduce even large stones to dust particles, UCI Health urologists report.

May 20, 2021
Super-pulsed thulium laser used on kidney stones.

A super-pulsed thulium fiber laser can break kidney stones into dust-like particles of 100 microns or less. Left image: The laser blasts a kidney stone. Right image: The same area after the particles have been suctioned away.

UCI Health urologists have tested a new laser technology capable of reducing even large kidney stones to dust that can be suctioned or flushed from the body.

The super-pulsed thulium fiber laser is “a game-changer,” says Ralph V. Clayman, MD, distinguished professor of urology and dean emeritus of the UCI School of Medicine. “It targets the water in the stones and can rapidly reduce a stone the size of your thumb into dust particles of 100 microns or less.”

The team of UCI urology researchers — led by Clayman, Pengbo Jiang, MD, and Zhamshid Okhunov, MD — reported their findings recently in the Journal of Endourology.

The prevalence of kidney stones in Americans has more than doubled in recent decades. Upwards of 10% of the U.S. population is likely to experience a kidney stone some time in their life. These crystallized mineral deposits can cause painful blockages that often require surgical intervention.

Easier, faster removal

As technology has evolved in recent years, lasers have been used to break up the stones in a procedure called lithotripsy, often without any incision. The urologist passes a laser-bearing, flexible scope to view the stone and fragment it. These laser fibers are as thin as three human hairs.

The thulium fiber laser can break kidney stones into pieces that are routinely 10 times smaller than those produced with a holmium laser, which is now used by most urologists. The smaller particles produced by the thulium laser are easier to flush or suction from the kidney.

“In our studies, the holmium laser was able to clear 50% to 60% of stone fragments,” says Clayman, an internationally known urologist and pioneer of minimally invasive surgical techniques that have revolutionized treatment of kidney and other urinary tract diseases.

“With thulium, we were able to clear more than 90% of fragments. If we can duplicate these results clinically, it opens the door for us to remove larger and larger stones with the ureteral approach, which is far less painful and costly than surgically removing them from the kidney,” he says.

Clayman hopes the technology will be widely available to kidney stone patients later this year for clinical applications at the UCI Health Center for Urological Care.

Leaders in innovation

Creating and adopting the latest technologies to improve care for patients has been a hallmark of the UCI Health urology team for two decades.

Clayman recently unveiled a breakthrough sensing device developed by the UCI team to prevent injury to the ureter during ureteral stone surgery. It works by controlling the force used during insertion of a protective sheath.

It was developed at the UCI Department of Urology’s Curiosity and Innovation Laboratory, which Clayman co-directs with department Chair Jaime Landman, MD, in collaboration with the School of Engineering and Michael Klopfer, PhD, technical director for California Plug Load Research Center at UCI.

Now, Clayman and fellow researchers are working on a disposable ureteroscope with a $72,000 grant from UCI Beall Applied Innovation. The small, flexible scope with a camera attached is passed along the urethra, bladder and ureter to locate stones in the kidney. It would use thulium laser technology and aspiration to suction the dust-like particles from the kidney.

Laboratory research using this approach has shown kidney stone clearance rates of up to 94%. “This would allow us to go after even very large kidney stones without the need to go through the kidney to remove them,” Clayman says. “With this approach, there’d be no incisions and far less chance of complications such as bleeding or infection.”

These advances represent a further evolution in natural orifice surgery, says Clayman. These incisionless procedures mean urologists can perform surgery on an outpatient basis, saving patients an overnight hospital stay and speeding recovery.

UCI Health is the clinical enterprise of the University of California, Irvine. Patients can access UCI Health at primary and specialty care offices across Orange County and at its main campus, UCI Medical Center in Orange, Calif. The 418-bed acute-care hospital, listed among America’s Best Hospitals by U.S. News & World Report for 20 consecutive years, provides tertiary and quaternary care, ambulatory and specialty medical clinics, as well as behavioral health and rehabilitation services. UCI Medical Center is home to Orange County’s only National Cancer Institute-designated comprehensive cancer centerhigh-risk perinatal/neonatal program and American College of Surgeons-verified Level I adult and Level II pediatric trauma center and regional burn center. It is the primary teaching hospital for the UCI School of Medicine. UCI Health serves a region of nearly 4 million people in Orange County, western Riverside County and southeast Los Angeles County. Follow us on Facebook and Twitter.