Management of renal calculi with minimal invasive technique: MicroPerc. Multicentric Analysis

Giovanni Di Lauro1, Carlo Molinari2, Giuseppe Romeo3, Leo Romis1, Antonio Ruffo3, Salvatore Mordente1, Alessandro Pane1, Daniele Masala1, Fabrizio Iacono3
  • 1 Ospedale Santa Maria delle Grazie (Pozzuoli)
  • 2 Ospedale San Camillo (Roma)
  • 3 Università Federico II (Napoli)


The purpose of our study is to describe our initial experience using Micro-Perc (Micronephrolithotripsy) technique for symptomatic renal stones. Micro-Perc represents the next step, after classical PCNL and MiniPerc, which achieves a reduction in complications rate such as bleeding related to the renal parenchyma and although extremely rare, the perforation of the colon during renal calculi treatment using percutaneous approach. MicroPerc allows to minimize the renal pelvis dilation that occurs during the percutaneous route, with the use of ballistic, laser or ultrasound as source of energy. Here we report our data concerning our experience from our stone centres in Italy.

Methods and results

We treated between March 2013 and January 2014, 24 adults and 2 children using MicroPerc for symptomatic renal stones. Patients mean age was 46,3yo±23,8SD (3 to 67yo).
The mean stone size was 2,5 cm ±0,9 SD (0,8 to 4 cm), the mean Body Mass Index(BMI)was 23,67 kg/m2 ±12,4SD(12,8 to 34 kg/m2).We evaluated perioperative and postoperative parameters in terms of: Operation Duration, Duration of hospitalization, Hemoglobin Drop and Percentage of Success. We considered Percentage of Success after one month from the surgery as Stone Free Rate (SFR) the absence of stones; as Clinical Insignificant Residual Fragment (CIRF) the residual stones not bigger then 4 mm; as Residual Stone(RS) presence of stones, bigger then 4 mm.
We used the three part all-seeing needle of diameter of 1,6 mm (4.85Fr) that is a bit larger than diameter of standard Chiba needle 1,3 mm. The all-seeing needle is made with a 3-way connector on is tip to allow in one channel the passage of the micro-optics with 120 degree lens with an integrated light lead. In a second channel the passage of the irrigation pump for water outlet. A third channel allows a holmium laser fiber passage.
The first step of the operative technique provide the patients in supine position and we placed a transurethral 6 Fr or 4.8 Fr ureteral catheter or 7 mono J stent if the stone diameter was > 2,5cm. The second step is the access to kidney pelvis under ultrasound or fluoroscopic guidance, through the micro-optical system and 3-part "all-seeing needle", with patients in prone position. We removed urethral Foley catheter and ureteral catheter in postoperative day 1, mono J stent was removed after 15 days from surgery. We placed in 3yo and 4,5yo patients also a 6 Fr nephrostomy with 4.7 Fr double J ureteral stent. Every patient was evaluated in post-operative day 1 and after 1 month with X-ray (KUB) and ultrasound of kidneys, ureters and bladder. All patients treated referred as main symptom pain after surgery with haematuria that was serious in only one patients, but it solved spontaneously. The main operation duration in minutes and hospitalization duration in hours was 65,3 min±28,4SD(35 – 110 min) and 39,3hours±8,2 SD(36 – 72 hours) respectively. The main haemoglobin drop was 0,8 g/dl ±0,4 SD(0,2 – 1,6 g/dl). In Three patients with multiple caliceal stones the procedure was completed after a second and a third percutaneous access with the all-seeing needle to the renal pelvis.
Totally stone free rate was achieved in 16 patients. We observed CIRF in 8 patients, residual stone bigger than 4 mm have been observed in 2 patients after one month from the treatment. Patients with CIRF were treated with Hydropinic therapy and off-label therapy with Alfuzosina. Patients with RS were treated with a session of Extracorporeal Shock Wave Lithotripsy.


The percutaneous approach for the renal stones larger than 2 – 2.5 cm or in stag horn lithiasis is so far been the correct indication. Micro-Perc has been recently introduced as safe technique with less invasiveness then standard PCNL, using a particular needle called: all-seeing needle. Micro-Perc provides in a single step percutaneous renal access under direct vision, stone disintegration and clearance of stones fragments. The Micro-Perc technique is then the logical development, with the aim to reduce surgical complications, of standard PCNL and Mini-Perc. The results of this multi-centric study provide that MicroPerc might take a part in the management of renal calculi. Routinary application is promising, but further studies comparing PCNL and MicroPerc are needed


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