Objective To evaluate the safety and efficacy of super mini-percutaneous nephrolithotomy (SMP) by ultrasound-guided renal access in pediatric with renal calculus.Methods From May to August 2015, 20 pediatric patients with upper tract stones underwent the SMP by ultrasound guidance.The patients aged 11-144 months , median age 31.5 months, The stone size ranged 0.8-2.5 cm, mean(1.48 ±0.59) cm.Among the 20 children, single pelvis stones were in 8, multiple stones in 10 and upper ureter stones in 2.All patients had no previous surgery treatment.The SMP system consists of a F6.0 -7.5 nephroscope and a modified F12-14 access sheath with suction-evacuation function.Nephrostomy tract dilation was performed up to F12-14 and lithotripsy procedure was performed by using pneumatic lithotripter.Nephrostomy tube or double J stent was placed only if clinically indicated.Results The stone size was 0.8-2.5 cm ,mean (1.48 ± 0.59)cm.Among the 20 children, there were 8 patients with single pelvis stone, 10 with multiple stones and 2 with upper ureter stones.All the patients were completed successfully without surgery conversion.Mean operative time ranged 6-40 minutes ,mean(17.6 ± 11.6) minutes.The stone free rate was 100％ after the evaluation in the postoperative day.The hemoglobin drop was 2-16 g/L,mean (7.6-± 4.1) g/L.No major complications occurred, neither patient required transfusion.The tubeless PCNL without double J stents and nephrostomy tubes placed were achieved in all patients.Only 14 patients had a ureter catheter placement for one day.The average hospital stay ranged 1-4 days, mean (2.4 ± 0.8) days.Conclusions SMP could be a safe and effective treatment for kidney stone up to 2.0 cm in pediatric cases with advantages of short recovery time, high stone free rate and no catheter placement.SMP could be the ideal procedure for children with upper urinary tract calculus.

Objective: To compare the safety and efficiency of totally ultrasonography-guided super-mini-percutaneous nephrolithotomy(SMP) in the treatment of upper urinary stone in adults and children(<14years). Methods: From May 2015 to July 2018, 81 cases of children(53%) and 71(47%) cases of adults with upper tract stones underwent the SMP by total ultrasound guidance. In the group of children, it’s including 53 male and 28 female with 85 channels in total, the patients age ranged from 10 months to 14 years, [mean (56.0±39.7) months], The stone size ranged from 0.8-3.5 cm, [mean (1.7±0.7)cm]. About stone distribution, 42 cases of pelvic stones, 25 cases of calyceal and pelvic stones, 5 cases of calyceal stones, 7 cases of upper uretaral stones, 1 case of upper ureteral and calyceal stones, 1 case of malformation with double renal pelvis and ureter. Urinary infection rate was 86.4%(70/81), positive rate of urinary culture was 39.5%(32/81). In the group of adults, it’s including 43 male and 28 female, the patients aged from 18 to 81 years, [mean (44.1±15.4)years], The stone size ranged from 1.0-3.0 cm, [mean (1.7±0.6)cm]. About Stone distribution, 19 cases of pelvic stones, 13 cases of calyceal and pelvic stones, 7 cases of calyceal stones, 24 cases of upper uretaral stones, 3 cases of upper ureteral and calyceal stones, 1 case of malformation with double renal pelvis and ureter. Urinary infection rate was 87.3%(62/71), positive rate of urinary culture was 26.8%(19/71). The patient was placed in the lithotomy position under general anesthesia. A 5F ureteric catheter was retrogradely inserted into the collecting system and urethral catheter was placed in the bladder. The patient was then turned prone. The selected calix was punctured under ultrasound guidance by 18G puncture needle and a 0.032 inch guidewire was inserted into the collecting system. Nephrostomy tract was established using Dilators(it was done in one step for 12F and in two steps for 14F). After the corresponding size of suction-evacuation sheath was placed, the sheath was connected to the specimen collection bottle via the oblique branch of a metal connector. The miniature endoscope was inserted into the sheath to observe the collecting system and stone fragmentation was completed by using YAG laser or pneumatic lithotripter. Stone free rate after surgery at 1day(SFR) and 1 month(1 month SFR), stone size, operative time(from starting fragmentation to the end of the surgery), hemoglobin drop and hematocrit drop in the first day after surgery, rate of surgecal complications, tubeless rate(totally tubless: no ureteric stent and nephrostomy tube; tubeless: no nephrostomy tube but ureteric stent), average length of hospital stay and urinary infection were recorded and compared. Results: In children group, mean operative time was (27.7±13.0)min(range 5-60 min), SFR and SFR at 1 month were 96.3%(78/81)and 98.8%(80/81), mean hemoglobin drop was (8.0±9.1)g/L(range 0-41 g/L), mean hematocrit drop was 0.026±0.029(range 0-0.135), totally tubeless rate was 86.4%(71/81), mean hospital stay was (2.5±0.9)days(range 1-5 days). Complications were observed in 9 cases and classified using Calvien grading system, Grade Ⅰ in 8 cases: postoperative fever in 4, hematuresis in 1, perirenal hematoma, postoperative distal ureteral stone in 1 cases and delayed recovery of intestinal function in 1 case, all had a spontaneous recovery without special managements; Grade Ⅲb in 1 case, massive ascites was discovered during the surgery, and rcovered by puncture drainage.In adult group, mean operative time was (31.2±15.3)min(range 7-80 min), SFR and SFR at 1 month were 97.2%(69/71) and 98.6%(70/71), mean hemoglobin drop was (11.9±8.7)g/L(range 0-32 g/L), mean hematocrit drop was 0.030±0.027(range 0-0.106), totally tubeless rate was 87.3%(62/71), mean hospital stay was(2.4±1.1)days(range 1-8 days), urinary infection rate was 87.3%(62/71), positive rate of urinary culture was 26.8%(19/71). Complications were observed in 4 cases, Grade Ⅰ in 3 cases: hematuresis in 2 and delayed recovery of intestinal function in 1 case, all had a spontaneous recovery without special managements; Grade Ⅲb in 1 case, postoperative distal ureteral stone in 1 cases and cured by ureteroscopic lithotripsy. According to data about Hb drop, risk of hemorrhage is lower in children than adult significantly(P<0.05). There is not significant difference in stone free rate, stone size, operative time, hematocrit drop, surgery complications, totally tubeless rate, stone complexity, average length of hospital stay and urinary infection(P>0.05). Conclusions With the characteristics of safe, efficacious and rapid recovery, super-mini-percutaneous nephrolithotomy(SMP) can be used as the first choice of the treatment for upper urinary stone both in adults and children.