CFAH logoKidney stones are rock-hard masses that may develop when crystals detach from urine. For majority of the individuals, kidney stones do not cause a major medical problem since they generally pass through the body’s urine stream without any trouble. But when stones become too big, one may experience intense pain. It may result in an infection, blood in the urine and even kidney failure.

A comparatively novel ultrasound probe procedure claims to have the maximum success rate for breaking down kidney stones in the lower ‘funnel’ region of the kidney, rather than the shock wave treatment used for several years, as per a review of studies. Nevertheless, the assessor warns that the studies were small, contained only about 214 patients, and the study method was of inferior quality.

The experts looked at the efficacy of three minimally invasive procedures. They are the older treatment known as extracorporeal shock wave lithotripsy (ESWL), the ultrasound procedure, or percutaneous nephrolithotomy (PCNL) and retrograde intrarenal surgery (RIRS), which utilizes a fiber-optic endoscope.

ESWL has apparently been in use since 1980. It transmits shock waves immediately to the kidney stone, breaking it up and allowing it to go through the urinary tract.

In the PCNL approach, a tiny opening at the person’s back is made so as to position the scope into the kidney and then pass a tube into the kidney through which the surgeon could put a laser ultrasound probe to eradicate or smash the stone into minute parts. The RIRS method uses a fiber-optic endoscope positioned through the urethra and into the bladder. The scope traces the stones, which could be broken up with an ultrasound probe.

Lead author Attasit Srisubat, M.D., at the Institute of Medical Research and technology assessment in Thailand, commented, “We found that the ultrasound probe had a much higher success rate in terms of stone-free kidneys than using shock waves. The success rate of using a fiber-optic endoscope did not differ significantly from shock wave treatment. However, the use of shock wave treatment did result in less time in the hospital and a shorter duration of treatment.”

In general, the success rate of every treatment assessed was not linked to the age, race or sex of the patients.

The three main funnels in the kidney are said to be the upper, middle and lower. The review concentrates on kidney stones in the lower funnel which could drain the bottom third of the kidney’s urine collecting system.

There are loads of risk factors for developing kidney stones. Some of them are family history, anatomical abnormalities of kidney diseases, and medications such as whether a person is taking calcium supplements or vitamin D supplements. This was mentioned by Srisubat. Medicine aids few people, but other patients may require a different approach. With the extended application of minimally invasive treatments, the want for open surgery to eliminate stones has apparently reduced.

Glenn Preminger, M.D., of the division of urologic surgery with Duke University Medical Center, routinely performs all three noninvasive forms of stone removal, remarked, “All of these treatments work relatively well depending on the size, location and composition of the stone. For certain stones that are large or are of a hard composition, they may not fragment well with shock wave treatment. For these we prefer to use an endoscopic means of stone removal.”

Anthony Smith, M.D., chief of the division of urology at the University of New Mexico School of Medicine, commented, “My overall impression is that we are using less and less shock wave treatment and more ureteroscopic intervention with the laser. With the new bi-directional ureteroscopes, we are able to treat larger stones in the upper urinary tract with great success.”

Smith is of the opinion that they have better success with lower pole stones using either ureteroscopic or percutaneous approaches.

The review appears in the latest issue of The Cochrane Library, a publication of The Cochrane Collaboration, an international organization that evaluates medical research.