Minimally invasive percutaneous nephrolitholapaxy (PCNL) as an effective and safe procedure for large renal stones


Mohamed F. Abdelhafez, Department of Urology, Tuebingen University, Konrad-Adenauer Street 48, Tuebingen 72072, Germany. e-mail:


Study Type – Therapy (case series)

Level of Evidence 4

What's known on the subject? and What does the study add?

The minimally invasive percutaneous nephrolitholapaxy (MIP) has shown high efficacy and safety for the management of small renal stones. It was initially developed to overcome a gap between the minimally invasive extracorporeal shockwave lithotripsy and invasive conventional percutaneous nephrolitholapaxy (PCNL) in the management of low stone burden but there is debate as to whether the MIP is also effective for larger stones.

The present study shows the high efficacy and safety of MIP, which is comparable to conventional PCNL in the treatment of stones of >20 mm, including complex staghorn stones.


  • • To evaluate the safety and efficacy of minimally invasive percutaneous nephrolitholapaxy (MIP) in the management of large and complex renal calculi.


  • • From January 2007 to March 2011, 73 patients with 83 renal units with large renal stones (>20 mm in diameter) were retrospectively evaluated.
  • • Stones were classified into simple (isolated renal pelvis or isolated calyceal stones) or complex (partial or complete staghorn stones, renal pelvis stones with accompanying calyceal stones).
  • • Stone-free rate, complications according to the modified Clavien system, decrease in haemoglobin, creatinine level, operative duration and hospital stay were compared for simple and complex renal calculi.


  • • The mean (sd) stone size was 36.7 (23.37) mm and mean operative duration was 99.2 (48.3) min.
  • • In all, 65 cases (78.3%) were stone-free after the first procedure and another 14 needed an auxiliary procedure (four second-look percutaneous nephrolitholapaxy, nine ureterorenoscopy, and one extracorporeal shockwave lithotripsy) to become stone-free, resulting in a 95.2% stone-free rate.
  • • Complications occurred in 22 procedures (26.5%), 17 of them were Clavien Grade 1 or 2 (20.5%), five were Grade 3 (6%). There were no Grade 4 or 5 complications.
  • • The only significant difference between complex and simple stones was the stone-free rate (96.9% vs 66.7%, P= 0.001).


  • • The MIP technique is effective and safe for larger stones with low morbidity, good success rate and reasonable operative duration.