Comparison of minimally invasive percutaneous nephrolithotomy and flexible ureteroscopy for the management of ≥1.5 cm renal stones in children

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Objective To evaluate the safety and efficacy of retrograde intrarenal surgery(RIRS)and minimally invasive percutaneous nephrolithotripsy (MPCNL)for the pediatric renal calculi (≥1.5 cm). Methods In the retrospective study, 97 patients with renal calculi(≥1.5 cm) underwent operation which is conducted by the same operative team from March 2011 to March 2016 .Among them, 40 patients were treated with RIRS, including 29 male and 11 female patients. 57 patients were treated with minimally invasive percutaneous nephrolithotripsy, including 45 males and 12 female patients. The mean stone size was (1.9±0.4)cm (ranging 1.5-3.0 cm) in the RIRS group and (2.1±0.5)cm(ranging 1.5-3.5 cm) in the MPCNL group. In RIRS group, 3 stones were stag-horn calculi. The diameter in 44 stones was more than 1.5 cm. Among them, 33 stones located in the renal pelvis and upper middle calyces. 11 stones located in the lower calyces. Multiple stones were found in 30 cases and single stone was found in 10 cases. 7 cases had the history of unilateral urolithiasis. 3 cases had the positive results of urine culture before operation. In MPCNL group, 7 stones were stag-horn calculi. The diameter in 60 stones was more than 1.5 cm. Among them, 56 stones located in the renal pelvis and upper middle calyces. 4 stones located in the lower calyces. Multiple stones were found in 41 cases and single stone was found in 16 cases. 4 cases had the history of unilateral urolithiasis. 2 cases had the positive results of urine culture before operation. The mean stone size in MPCNL was larger, but the difference was not statistically significant (P>0.05). No statistical significance was found between the two groups in sex, age, preoperative urine, positive culture, patients with renal staghorn calculi, percentage of multiple calculi, stones in lower calyx and operation history of the same side(P>0.05). The urine white blood cells between the two groups were statistically significant (P<0.01), but the urine white blood cells in RIRS before placing double J stent had no significant difference with those in MPCNL. Results In RIRS group, The mean operative time was(90.2±17.8) minutes. The mean hemoglobin deficit was (7.9±7.9)g/L. The complication rate was 7.5%(3/40). The postoperative hospital stay was (5.0±2.3)days. The hospitalization cost was (42 994.1±9 747.8)yuan.Stone-free rates after one session was 72.5%(29/40). After second procedure, stone-free rates were up to 90.0%(36/40). In MPCNL group, the mean operative time was (77.8±15.6)min. The mean hemoglobin deficit was (10.0±7.1)g/L. The complication rate was 24.6%(14/57). The postoperative hospital stay was (8.0±2.5)days. The hospitalization cost was(24 626.3±6 324.7)yuan. The stone-free rate after one session was 82.5%(47/57). After second procedure, stone-free rates were up to 94.7%(54/57). In statistics, there was no significant difference in hemoglobin drop, the stone-free rate on one session and the final stone-free rates(P>0.05). But significant difference existed in operative time, complications rate, postoperative hospitalization time and hospitalization cost(P<0.05). Conclusion Both RIRS and MPCNL are feasible, safe and minimally invasive way to treat renal calculi(≥1.5 cm) in pediatric patients.The stone-free rates between the two groups are comparable. RIRS has an advantage in postoperative hospitalization time and postoperative complications. MPCNL takes the advantage of operation time, hospitalization cost and needn't routinely places the double-J ureteral stent. Key words: Flexible ureteroscopy; Percutaneous nephrolithotomy; Renal calculi; Children