Percutaneous nephrolithotomy (PCNL) or retrograde intrarenal surgery (RIRS) are the most appropriate approaches for treating lower pole kidney stones 1 to 2 cm in size, according to a new systematic review and meta-analysis published in the Journal of Urology.

For lower pole stones smaller than 1 cm, RIRS outperforms shock wave lithotripsy (SWL).

The study of data from 15 randomized controlled trials (published after 2000) of moderate-to-high quality, PCNL and RIRS resulted in 5.9- and 3.0-fold higher stone-free rates, respectively, compared with SWL in patients with 1 to 2 cm stones. SWL was associated with shorter operative times and fewer complications than PCNL (for example, more blood transfusions were needed after PCNL), but required more retreatment sessions (using any procedure). Hospital length of stay was longer for PCNL compared with RIRS and SWL.

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“The decision between the two approaches (PCNL or RIRS) should be individual, based on the anatomical parameters, the comorbidity and the preferences of each patient,” Panagiotis Kallidonis, MD, PhD, of the University of Patras in Greece, and colleagues wrote. Other important factors, such as stone volume and hardness, could not be assessed, which was a study limitation, the authors noted.

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RIRS was 1.7-fold more effective at removing stones up to 1 cm in the lower pole than SWL. (PCNL was never employed for these small stones.) RIRS took about 11 minutes longer to perform than SWL, but complication rates were similar and SWL required more retreatment.

“This observation underlines the higher difficulty of SWL to treat the [lower pole stones] in comparison to stones located in other sites of the pelvicalyceal system,” Dr Kallidonis’ team stated.


Kallidonis P, Ntasiotis P, Somani B, et al. Systematic review and meta-analysis comparing percutaneous nephrolithotomy, retrograde intrarenal surgery and shock wave lithotripsy for lower pole renal stones <2 cm in maximum diameter. J Urol. doi: 10.1097/JU.0000000000001013