There is a global increase in the prevalence of urolithiasis in children attributed to lifestyle changes, dietary habits, climate changes, childhood obesity, and the wider availability of ultrasonography. The rising incidence of the disease with its recurrent nature emphasizes the need for minimally invasive therapeutic options. Patients in whom RIRS has been performed in the last four years with increasing experience will be presented, and complications, stone-free rates, and technical details will be discussed.

This retrospective Cohort study included children who underwent RIRS. Medical history, serum electrolytes, midstream urine culture, urinalysis, serum creatinine, complete blood count, and coagulation assessments were performed preoperatively. Ultrasonography (USG) was performed three months, 6 months, and 1 year after the procedures to evaluate stone recurrence and hydronephrosis. The investigators analyzed the stone-free rate ,complications, and the conversion to open procedure

There has been a worldwide rise in the prevalence of urolithiasis in children, which is linked to changes in lifestyle and dietary habits, climate changes, childhood obesity, and the increased availability of ultrasonography (1). In pediatric stone disease, it is crucial to evaluate the underlying reasons, which may include metabolic disorders, anatomical anomalies, and infection, to avoid higher recurrence of stones after treatment (2). The increasing incidence and recurrence of this disease highlights the necessity for minimally invasive therapeutic solutions. Retrograde intrarenal surgery (RIRS) is gaining new indications owing to advanced laser and endoscopic technology, resulting in a constant rise in the number of procedures (3).

Routine RIRS has been performed in our clinic for the last 15 years with increasing rates. Patients in whom RIRS has been performed in the last three years with increasing experience will be presented, and complications, stone-free rates, and technical details will be discussed.

This retrospective cohort study included children who underwent RIRS between January 2019 and December 2022 at the Ankara Bilkent City Hospital, University of Health Science, Ankara, Turkey. The inclusion criteria were pediatric patients with kidney stones who underwent RIRS. The exclusion criteria were cases that were converted to open surgery, cases in which RIRS could not be performed because of anatomical reasons, and cases in which lower pole stones could not be reached with RIRS. The Ethics Committee of the Institution approved this study (E2-23-5305). All patient details were identified, and all patients provided written informed consent to participate in the study. Medical history, serum electrolytes, midstream urine culture, urinalysis, serum creatinine, complete blood count, and coagulation assessments were performed preoperatively. Plain abdominal film and ultrasonography/computer tomography scan examinations were also performed. Patients with preoperative positive urine culture results received a complete course of culture-specific antibiotics before RIRS Prophylactic antibiotic treatment with cephazolin was administered to all patients prior to surgery.

Surgical treatment was indicated when there was an obstruction, infection, failure of spontaneous stone passage, or stones larger than 7 mm and in the presence of increasing or unremitting colic.

All RIRS procedures were performed under general anesthesia with direct videoscopic and fluoroscopic guidance. All procedures were performed by the same surgeon. Semirigid ureteroscopy (4.5 Fr R. Wolf, Knittlingen, Germany) or flexible ureteroscopy (Karl Storz FLEX-X, Tuttlingen, Germany) was performed to place an access sheath. The decision to use a flexible or semirigid ureteroscope depended on the location of the stones. A flexible ureteroscope was used for lower pole stone, wherease a semirigid ureteroscope was preferred for renal pelvic or upper pole stones. In our practice, all children undergoing RIRS for stone disease received cephazolin. Perioperative antibiotic treatment was continued for a week following surgery. If a double J (JJ) stent was inserted, antibiotic prophylaxis was continued and ceased after removal of the JJ stent. A manual irrigation pump system was used for hydrodilation of the ureter during ureterorenoscopy. If this was not enough to pass the ureteroscope, the investigators placed a JJ catheter for passive dilatation. Ureteral active coaxial or balloon dilation was not performed. The investigators used isotonic fluid at body temperature to avoid hypothermia and hyponatremia during the procedures. The urinary bladder was maintained at low pressure with a 14-F suprapubic angiocatheter in all patients. Stones were fragmented using a holmium-YAG laser (Litho Quanta System, Italy) and grasped by a stone basket when applicable. Contrast injection was performed at the end of the procedures to confirm the absence of extravasation and stone-free status. The decision to place a postoperative uretral stent was made according to visible mucosal ureteral trauma or edema at the end of the procedure. The extracted stone specimens were submitted for stone analysis. All patients were discharged if fever was not detected the day after the procedures. Medical therapy and dietary planning were provided postoperatively on the basis of the composition of the stones. Ultrasonography (USG) was performed three months, six months, and one year after the procedures to evaluate stone recurrence and hydronephrosis. The investigators analyzed the stone-free rate, complications, and conversion to the open procedure. Statistical analysis was performed using the Chi-Square and ANOVA tests, p: 0.05 was considered statistically significant.

Inclusion Criteria:

• The inclusion criteria were pediatric patients with kidney stones who underwent RIRS.

Exclusion Criteria:

• The exclusion criteria were cases that were converted to open surgery, cases in which RIRS could not be performed because of anatomical reasons, and cases in which lower pole stones could not be reached with RIRS.

One hundred and five patients (49 boys and 56 girls) with a median age of 6,66+5,27 years (0,25-17,6 years) were treated with RIRS between January 2019 and December 2022. The RIRS procedure could not be performed in 15 cases, whereas it could be performed in 90 cases.

Describe the IPD sharing plan, including what IPD are to be shared with other researchers.