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L. Defidio, M. De DominicisStone sizeStone compositionStone locationAgeCongenital anomaliesSecondary anomaliesTable 1.Indications for retrograde treatment of renal stones in children≤ 2 cmRefractory to ESWLInferior calyx (lower pole)≥ 12 mthAbsence of upper obstructive pathologiesSolitary kidneyCoagulation disorderEctopic kidneycurrently urologists can benefit from the whole spectrumof stone management alternatives also in children.Although ESWL is still the most important procedure fortreating urinary stones, advances in flexible endoscopes,intracorporeal lithotripsy, and extraction instrumentshave led to a shift in the range of indications (3).The indications for retrograde treatment of the renalstone in child are showed in Table 1.According to the location of the stone the treatment canbe done with the rigid or flexible ureteroscope. The safetyand efficacy of ballistic or holmium:YAG laserlithotripsy make intracorporeal lithotriptor the treatmentof choice.Usually, a paediatric cystoscope is used to place a 5 Fropen-ended catheter to the level of the intramural ureter,and a low pressare ureteropyelogram is taken. A 0.035inch guidewire is positioned in the renal pelvis throughthe open-ended catheter and used as a safety wire duringthe procedure and for placing a ureteral catheter at theend of the procedure.The second dual flex guidewire is advanced in the ureterthrough the working channel of the 6 or 8 Fr semirigidureteroscope. The scope is then advanced between thetwo guidewires under endoscopic guidance up to thekidney.This manoeuvre allows an active dilation of the ureterfacilitating a subsequent flexible ureterorenoscopy orfragments removal. Any difficulty in negotiating theureteric orifice was resolved by rotating the instrumentatraumatically by 180° during insertion. Ureteric dilatorswere very rarely used and only when the meatus wasimpossible to negotiate.Current ureteroscopic intracorporeal lithotripsy devicesand stone retrieval technology allow for the treatment ofcalculi located throughout theintrarenal collecting system. Ifthe stone is located in theupper calyx, middle calyx orin the renal pelvis a lithotripsywith a semirigid ureteroscopeis recommended tostart. Lower pole calculi arefragmented with a 200µholmium laser fiber by a 7.5Fflexible ureteroscope.For those patients in whomthe laser fiber reduces thescope deflection, precluding are-entry into the lower polecalix, a 1.5, 1.9 or 2.2 tiplessnitinol basket is used to displace the lower pole calculusinto a more favorable position, allowing easier fragmentation(relocation technique) (4).This manoeuvre is essential to preserve the ureterorenoscope(Figure 1).The use of a ureteral access-sheath, during a flexibleureterorenoscopy, is suggested to improve the irrigantflow and visibility.The ureteral access-sheath can induce transient ureteralischemia and promote an acute inflammatoryresponse, but it also prevents potentially harmful elevationsin intrarenal pressure reducing the risk of urosepsis.It has also has the potential to improve stone-freerates by allowing passive egress or active retrieval offragments.To obtain stone fragments is essential for biochemicalanalysis. The stone composition may give significantinformation to prevent the high rate of recurrence, withdietary modification and specific therapy.Usually, a ureteral open-ended catheter is left in placeand removed in the next 24-72 h. If ureteric dilation wasused or the procedure has been complicated, a doublepigtailureteric stent is left in place for 1 week.Successful outcomes for the retrograde treatment of renalcalculi are similar to the ones obtained in the adult population(Table 2).The retrograde semirigid and flexible ureteropyeloscopy,using a small calibre ureteroscope, are a valuable techniquefor kidney stones treatment in children. Withexcellent technique and meticulous attention to details,the significant complications are rare. Reported complicationsare infrequent and generally minor. Intra-operativeureteric injuries usually consist of ureteric perforationwith the guide-wire.Table 2.Stone free rate in ureteroscopic treatment of kidney stones in child.C an n o n G M (J Endourol 2007) (5) 93% for stone < 15 mm No relocation technique33% for stone > 15 mmSmal d o n e M C (J Urol 2007) (6) 91% Mean stone size 8.3 mmM i n ev i c h E (J Urol 2005) (7) 98% Non stone size evidence54Archivio Italiano di Urologia e Andrologia 2010; 82, 1