Is mPCNL more effective than RIRS for medium-sized renal calculi?
For medium-sized kidney stones (roughly 1 to 3 cm), miniaturized percutaneous nephrolithotomy (mPCNL, a keyhole surgery through the back) and retrograde intrarenal surgery (RIRS, a scope passed up through the urinary tract) are the two main minimally invasive options. The short answer: mPCNL is better at getting the stone out in one session, but RIRS is gentler on the body. A 2026 meta-analysis of randomized controlled trials found mPCNL had a significantly higher single-session stone-free rate, while RIRS showed a trend toward fewer overall complications, less blood loss, and shorter hospital stays 68.
What the research says
The strongest evidence comes from a 2026 meta-analysis that pooled only randomized controlled trials, which avoids the selection bias of earlier reviews that mixed in observational data. Across 30 trials and 4,173 patients, mPCNL achieved a significantly higher single-session stone-free rate than RIRS (risk ratio 0.92, 95% CI 0.88 to 0.96, p < 0.001) 68. In plain terms, mPCNL was more likely to leave the patient stone-free after one procedure.
On safety, the picture tilts the other way. RIRS showed a trend toward a lower overall complication rate, though this did not quite reach statistical significance (risk ratio 0.79, 95% CI 0.63 to 1.01, p = 0.057). RIRS also had reduced blood transfusion requirements, smaller drops in hemoglobin, and shorter hospital stays 68. So the trade-off is real: mPCNL wins on stone clearance, RIRS wins on recovery and bleeding risk.
Other sources help explain why these two approaches differ. PCNL is described as the gold standard for large and complex stones, and studies of puncture technique during PCNL found that papillary versus non-papillary access made no significant difference in bleeding or transfusion rates, suggesting the access path itself is not the main driver of complications 12. For the PCNL side, a meta-analysis of 28 randomized trials found that tubeless PCNL reduced hospital stay, pain, and analgesic use compared with standard PCNL, with no significant difference in stone-free rate or major complications 5.
On the RIRS side, technique matters too. A meta-analysis of 8 studies (998 patients) found that certain intraoperative patient positioning strategies raised stone-free rates compared with standard positioning (risk ratio 1.20, 95% CI 1.12 to 1.28, p < 0.001) 3. And for stones 2 cm or smaller, suction-assisted flexible ureteroscopy improved 30-day stone-free rates and reduced fever and sepsis compared with conventional sheaths 4. These findings suggest that how RIRS is performed can narrow the gap with mPCNL, though the head-to-head trials still favor mPCNL on single-session clearance 68.
What to ask your doctor
- Given my stone size and location, is mPCNL or RIRS a better fit for me, and why?
- How does the higher single-session stone-free rate of mPCNL weigh against the lower complication rate and faster recovery of RIRS in my case?
- What is my personal risk of needing a second procedure if I choose RIRS?
- Are there techniques (such as positioning or suction-assisted devices) that could improve my stone-free odds with RIRS?
- How do my other health conditions affect the bleeding and infection risks of each option?
This question is drawn from common patient questions about Urology and answered using cited medical research. We do not provide individualized advice.