Evaluation of different percutaneous nephrolithotomy procedures applied in pediatric patients younger than 18 years old

Objective: In this study the aim was to compare the demographic, perioperative and postoperative data of pediatric patients under 18 year who underwent standard percutaneous nephrolithotomy (PNL), mini percutaneous nephrolithotomy (mini-PNL), ultra-mini percutaneous nephrolithotomy (UMP) and micro percutaneous nephrolithotripsy (micro-PNL) procedures in our clinic. Materiel and Method: Data of pediatric patients under the age of 18 were analyzed retrospectively who underwent different PNL procedures between March 2011 and October 2015 in Dicle University Medical Faculty Urology Clinic. The demographic characteristics, perioperative and postoperative data of the patients were recorded. Patients were stratified into four groups according to dilatation diameter during operation in terms of standard PNL (30 Fr-24 Fr) (Group 1), mini-PNL (20 Fr-16 Fr) (Group 2), UMP (14 Fr-12 Fr) (Group 3) and micro-PNL (4,8 Fr) (Group 4). Age, gender, stone size, stone location, stone opacity, degree of hydronephrosis, access technique, degree of dilatation, nephroscope diameter, operation time, fluoroscopy time, amount of bleeding, stone-free status, duration of hospitalization, drainage method, diversion method, additional interventions and later stone-free status and complications degrees were compared between each group. Results: There were 73 patients in Group 1, 75 patients in Group 2, 78 patients in Group 3 and 46 patients in Group 4. Two patients in Group 2 and one patient in Group 3 underwent bilateral PNL in the same session. Gender distribution male/female was 39/34 in Group 1, 45/30 in Group 2, 53/25 in Group 3, 23/23 in Group 4 and statistically significant difference was not observed between groups (p=0,165). Mean age of the patients was 12,9±3,9 years in standard PNL group, 7,9±5,2 years in mini-PNL group, 3,9±3,3 years in UMP group, 6,1±4,9 years in micro-PNL group and statistically significant difference was observed between groups (p<0,001). The mean stone size was 40,9±16,1 mm, 26,2±9,2 mm, 19,4±7,7 mm, 16±5,3 mm respectively and statistically significant difference was observed between groups (p <0,001). Mean operation time was 56,3±21,6 minutes in Group 1, 49,9±15,3 minutes in Group 2, 57,3±16,2 minutes in Group 3, 61,7±22,6 minutes in Group 4 and statistically significant difference was observed between groups (p=0,006). Mean fluoroscopy time was 1,7±1,1 minutes Group 1, 1,5±0,9 minutes Group 2, 2,3±1,3 minutes Group 3, 1,6±1,2 minutes Group 4, besides statistically significant difference was detected (p<0,001). Mean duration of hospitalization was 3,6±2,1 days (1-14) in general; 3,2±1,7 days in Group 1, 3,7±2,3 days in Group 2, 3,7±2 days in Group 3, 3,9±2 days in Group 4 and statistically significant difference was not observed between groups (p=0,222). Mean hemoglobin decrease was 1,4±1,5 gr/dL, 1,1±1,2 gr/dL, 0,8±0,9 gr/dL, 0,5±0,9 gr/dL respectively and statistically significant difference was observed between groups (p<0,001). The dilatation diameter and hemoglobin decline were proportional and hemoglobin was found to decrease more significantly especially at diameters of 20 Fr and above (p=0,003). At the first month assesment after operation stone-free status was achieved 39 (%53,4) patients in Group 1, 60 (%80) patients in Group 2, 64 (%82,1) patients in Group 3, 37 (%80,4) patients in Group 4 and statistically significant difference was observed (p<0,001). Additional intervention was performed for 22 patients in Group 1, 10 patients in Group 2, 2 patients in Group 3, 4 patients in Group 4. The stone-free rate after additional intervention was 61 (%83,6) patients in Group 1, 70 (%93,3) patients in Group 2, 66 (%84,6) patients in Group 3, 41 (%89,1) patients in Group 4 and statistically significant difference was not observed between groups (p=0,093). Complications were observed in 70 (%25,7) patients. The distribution of complications according to Modified Clavien classification Grade 1 complication was seen 3 (%4,1) patients in Group 1, 2 (%2,7) patients in Group 2, 4 (%5,1) patients in Group 3, 3 (%6,5) patients in Group 4 and Grade 2 complication was seen 7 (%9,6), 12 (%16), 9 (%11,5), 5 (%10,9) patients respectively. Grade 3a complication was seen 2 (%2,7), 6 (%8), 2 (%2,6), 2 (%4,3) patients respectively. Grade 3b complication was seen 8 (%10,9) patients in standard PNL, 2 (%2,7) patients in mini-PNL, 1 (%2,2) patient in micro-PNL and was not seen in UMP group. Grade 4 complication which only colon perforation was seen 1 (%1,4) patient in Group 1, 1 (%1,3) patient in Group 2. There was no statistically significant difference for complication rate between these groups (p=0,374). Blood transfusion was needed 6 (%8,2) patients in Group 1, 9 (%12) patients in Group 2, 2 (%2,6) patients in Group 3, 1 (%2,2) patient in Group 4. Perioperative bleeding occurred in 4 patients in Group 1 and 1 patient in Group 4, which required quitting the operation. Conclusion: Although similar success and complication rates were seen between different PNL procedures for under 18 year pediatric group in our study; bleeding amount statistically significant was lower in UMP and micro-PNL. In this age group, similar success and efficiency can be achieved with lower bleeding rate via using miniature instruments during access, dilatation and fragmentation. Keywords: Percutaneous nephrolithotomy, Mini-PNL, Ultra-mini-PNL, Micro-PNL, Pediatric nephrolitiazis