title: Percutaneous endoscopic treatment for urinary stones in pediatric patients: where we are now.
abstract: BACKGROUND
  Percutaneous nephrolithotomy (PCNL) has been adopted for pyelo-calyceal stones treatment in pediatric patients, starting from the 90's. Very recently, miniaturization of endoscopic instruments allowed less invasive procedures with low complication rate. We reviewed our experience on upper tract stone treatment utilizing two different percutaneous accesses, focusing on the recent new miniaturized devices offered for pediatric renal stones.
  
  
  METHODS
  Patients presenting upper tract urinary stones observed from January 2011 to December 2015 and treated by percutaneous renal access were prospectively evaluated: age, sex, metabolic issues, associated abnormalities, treatment modalities, hospital stay and complication rate were recorded in a specific database. Two different endourological percutaneous modalities were adopted, depending to the stone size and position. PCNL was performed through a direct calyceal puncture under ultrasonographic and fluoroscopic guidance and Amplatz access dilatation till 24 Fr. Ballistic energy was used for fragmentation. Micropercutaneous (Microperc) procedure was recently offered utilizing a 4.85 Fr metallic needle and Holmium:YAG laser lithotripsy under direct vision through a 0.9 mm high resolution optic flexible wire connected with a telescope.
  
  
  RESULTS
  Thirty-eight percutaneous access to pyelo-calyceal renal stones were performed on a total of 108 children treated for upper tract stones, aged 4 to 18 years (mean age 7.5 years). The overall number of procedures was 144 (36 repeated procedures). Cystinuria was diagnosed in 5 patients. PCNL was adopted in 28 patients, Microperc was utilized in 8 patients. Hemoglobin dropdown was limited to 1.20±0.80 mg% in PCNL and was not significant in Microperc. No blood transfusion was needed. No significant complications were observed. Stone free rate or minimal not significant residuals were achieved in 82% of PCNL and in 87.5% of Microperc, after a single procedure.
  
  
  CONCLUSIONS
  Percutaneous endoscopic treatment of renal calculi is feasible in pediatric age, with high success rate in a single step. Advanced miniaturized endoscopic devices as Microperc guarantee high efficacy and reduced complication rate, but endo-urological experience and adequate learning curve are required, especially in small body weight children. Centralization of these patients in Pediatric Stone Centers is welcomed to optimize results and reduce risks.
authors.affiliation: Division of Pediatric Urology, "Bambino Gesù" Children's Hospital, Rome, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Caione
authors.affiliation: Division of Pediatric Urology, "Bambino Gesù" Children's Hospital, Rome, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Collura
authors.affiliation: Division of Pediatric Urology, "Bambino Gesù" Children's Hospital, Rome, Italy.
authors.forename: Michele
authors.initials: M
authors.lastname: Innocenzi
authors.affiliation: Division of Urology, "Cristo Re" Hospital, Rome, Italy.
authors.forename: Mauro
authors.initials: M
authors.lastname: De Dominicis
authors.affiliation: Division of Pediatric Urology, "Bambino Gesù" Children's Hospital, Rome, Italy.
authors.forename: Simona
authors.initials: S
authors.lastname: Gerocarni Nappo
authors.affiliation: Division of Pediatric Urology, "Bambino Gesù" Children's Hospital, Rome, Italy.
authors.forename: Nicola
authors.initials: N
authors.lastname: Capozza
keywords: Percutaneous nephrolithotomy (PCNL); children; endoscopy; micropercutaneous (Microperc); renal stones