Appropriate kidney stone size for ureteroscopic lithotripsy: When to switch to a percutaneous approach - Beyond the Abstract

Thanks to the recent advances in endoscopic technology, flexible ureteroscopy (fURS) has become a more efficient treatment for whole upper urinary tract stones. Percutaneous nephrolithotomy (PNL) is currently the first-line recommended treatment for large kidney stones ≥ 20 mm and it has an excellent stone-free rate for large kidney stones. However, its invasiveness is not negligible considering its major complication rates.

Staged fURS is a practical treatment for such large kidney stones because fURS has a
minimal blood transfusion risk, short hospitalization and few restrictions on daily routines. However, as the stone size becomes larger, the stone-free rate decreases, and the number of operations required increases. Therefore, in our opinion, staged fURS is a practical option for kidney stones 20 to 40 mm.

The stone size between 20 and 40 mm is now the boundary area between fURS and PNL. The treatment option should be determined according to individual conditions. Now, we select the Galdakao-modified supine Valdivia (GMSV) position during the surgery. The GMSV position can make use of combined or subsequent transurethral and percutaneous access to the urinary tract. The GMSV position does not need to change the patient position. Also, it provides better descending drainage, retrieval of the stone fragments from percutaneous tract, and decompression of the intrarenal pressure.

In this paper, we proposed a new treatment algorithm for kidney stones. We simply select the treatment option with no distinction regarding the stone position (upper/middle calices or lower pole), because the current fURS instruments can easily reach to the all calices, including the lower calyx, and can clear away the stone fragments by using a basket. Basically, we recommend endoscopic treatment for kidney stones, because residual fragments after shock wave lithotripsy (SWL) frequently do not pass spontaneously and often lead the stone recurrence. Depending on the operator’s skills and the stone shape/position/component, stones up to 40 mm can be treated sufficiently by fURS monotherapy, although staged operations may be required. We also recommend using a combination of mini-PNL and fURS for larger stones, especially for staghorn stones, because the fURS can access each calyx, where the percutaneous antegrade approach is difficult. This is associated with a major advantage in terms of clearing the stone burden. Multi-tract PNL has also been reported as a successful treatment. Multi-tract procedures may cause more complications, but if necessary, should be considered for appropriate cases.

Written by:
Ryoji Takazawa, MD, PhD
Tokyo Metropolitan Ohtsuka Hospital, Department of Urology, Tokyo.

Abstract: Appropriate kidney stone size for ureteroscopic lithotripsy: When to switch to a percutaneous approach

email news signup