Song 2015

Methods	Study design: parallel‐group randomised controlled trial. Setting: single centre/China. Dates when study was conducted: September 2009 to September 2012.
Participants	Inclusion criteria: renal calculi confirmed by spiral CT, 7‐36 months old, stone diameter < 4.5 cm, no previous SWL. Exclusion criteria: renal anatomical abnormalities, ureteropelvic junction stenosis, pyonephrosis combined with stones, or isolated kidney. Diagnostic criteria: US, spiral CT, IVU. Total number of participants randomly assigned: 78. Group A (Standard PCNL) Number of participants randomly assigned: 38. Age (mean): 20.10 ± 7.22 months. Gender (M/F): not reported. Group B (Tubeless Mini PCNL) Number of participants randomly assigned: 40. Age: 20.30 ± 6.35 months. Gender (M/F): not reported.
Interventions	Group A (n = 38): in PCNL, the method of surgery was the same, except post procedure the nephrostomy tube was inserted. Group B (n = 40): in MPCNL 18 G (gauge) biopsy needle was inserted at the posterior axillary line, the ureteral catheter was expanded by a fascia dilator to F14 or F16 while the sheath was left in place. The paediatric nephroscope or ureteroscope was then inserted, and the stones were smashed by holmium laser and picked out by clamps or washed out by lavage fluid. Co‐interventions: ureteral and Foley catheters.
Outcomes	Stone clearance How measured: CT or B‐mode US. Residual stones of ≤ 4 mm were considered negligible. Time points measured: at 1,3,6 and 12 months postoperatively. Time points reported: reported in counts and percentages but no time points. Subgroup: none. Complications How measured: perioperative evaluation. Time points measured: some during surgery, some not reported. Time points reported: not reported. Subgroup: none. Secondary procedures How measured: not reported. Time points measured: not reported. Time points reported: not reported. Subgroup: none.
Notes	Funding Sources: not stated Declaration of interests: not stated
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote from publication: "Preschool children were randomised into MPCNL and standard PCNL groups by generation of a random number table".
Allocation concealment (selection bias)	Unclear risk	Quote from publication: "Surgical nurses randomly selected an envelope containing each patient's group". Unclear whether envelopes were sequentially numbered, opaque and sealed.
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Not described.
Blinding of outcome assessment (detection bias) Subjective outcomes	Unclear risk	Not described.
Blinding of outcome assessment (detection bias) Objective outcomes	Low risk	Objective outcomes are not likely to be influenced by lack of blinding.
Incomplete outcome data (attrition bias) Stone free rate	Unclear risk	3/38 (7.8%) and 5/40 (12.5%) participants in PCNL and mini‐PCNL group were not included in the analysis, respectively.
Incomplete outcome data (attrition bias) Serious adverse events or complications of treatment	Unclear risk	3/38 (7.8%) and 5/40 (12.5%) participants in PCNL and mini‐PCNL group were not included in the analysis, respectively.
Incomplete outcome data (attrition bias) Secondary procedures	Unclear risk	3/38 (7.8%) and 5/40 (12.5%) participants in PCNL and mini‐PCNL group were not included in the analysis, respectively.
Incomplete outcome data (attrition bias) Hospital stay	Unclear risk	No information given.
Incomplete outcome data (attrition bias) Pain	Unclear risk	No information given.
Selective reporting (reporting bias)	Unclear risk	The outcomes were not prespecified and no published protocol available.
Other bias	Low risk	Not detected.

Abbreviations

CT: computerised tomography; DUS: distal ureteric stone; IVU: intravenous urethrogram; KUB: kidney ureter bladder; MPCNL: mini percutaneous nephro lithotomy; NCCT: non‐contrast computerised tomography; RIRS: retrograde intrarenal surgery; SWL: shock wave lithotripsy; TUL: trans‐urethral lithotripsy; ULT: ureteroscopic lithotripsy; URS: ureteroscopy; US/USS: ultrasound; XR: x‐ray.