title: Tract Sizes in Miniaturized Percutaneous Nephrolithotomy: A Systematic Review from the European Association of Urology Urolithiasis Guidelines Panel.
abstract: Miniaturized instruments for percutaneous nephrolithotomy (PNL), utilizing tracts sized ≤22 Fr, have been developed in an effort to reduce the morbidity and increase the efficiency of stone removal compared with standard PNL (>22 Fr).
  
  
  
  We systematically reviewed all available evidence on the efficacy and safety of miniaturized PNL for removing renal calculi.
  
  
  
  The review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses statement. Since it was not possible to perform a meta-analysis, the data were summarized in a narrative synthesis.
  
  
  
  After screening 2945 abstracts, 18 studies were included (two randomized controlled trials [RCTs], six nonrandomized comparative studies, and 10 case series). Thirteen studies were full-text articles and five were only available as congress abstracts. The size of tracts used in miniaturized procedures ranged from 22 Fr to 4.8 Fr. The largest mean stone size treated using small instruments was 980mm2. Stone-free rates were comparable in miniaturized and standard PNL procedures. Procedures performed with small instruments tended to be associated with significantly lower blood loss, while the procedure duration tended to be significantly longer. Other complications were not notably different between PNL types. Study designs and populations were heterogeneous. Study limitations included selection and outcome reporting bias, as well as a lack of information on relevant confounding factors.
  
  
  
  The studies suggest that miniaturized PNL is at least as efficacious and safe as standard PNL for the removal of renal calculi. However, the quality of the evidence was poor, drawn mainly from small studies, the majority of which were single-arm case series, and only two of which were RCTs. Furthermore, the tract sizes used and types of stones treated were heterogeneous. Hence, the risks of bias and confounding were high, highlighting the need for more reliable data from RCTs.
  
  
  
  Removing kidney stones via percutaneous nephrolithotomy (PNL) using smaller sized instruments (mini-PNL) appears to be as effective and safe as using larger (traditional) instruments, but more clinical research is needed.
authors.affiliation: Department of Urology, Skåne University Hospital, Malmö, Sweden.
authors.forename: Yasir
authors.initials: Y
authors.lastname: Ruhayel
authors.affiliation: Department of Urology, Sen Jorj Austria Hospital, Istanbul, Turkey.
authors.forename: Abdulkadir
authors.initials: A
authors.lastname: Tepeler
authors.affiliation: Department of Urology, Skåne University Hospital, Malmö, Sweden.
authors.forename: Saeed
authors.initials: S
authors.lastname: Dabestani
authors.affiliation: Academic Urology Unit, University of Aberdeen, Aberdeen, UK.
authors.forename: Steven
authors.initials: S
authors.lastname: MacLennan
authors.affiliation: Department of Urology, Region Hospital, České Budějovice, Czech Republic; Department of Urology, First Faculty of Medicine, Charles University in Prague, Prague, Czech Republic.
authors.forename: Aleš
authors.initials: A
authors.lastname: Petřík
authors.affiliation: Department of Urology, Dr. Lutfi Kirdar Kartal Research and Training Hospital, Istanbul, Turkey.
authors.forename: Kemal
authors.initials: K
authors.lastname: Sarica
authors.affiliation: Department of Urology, Medical University Vienna, Vienna, Austria.
authors.forename: Christian
authors.initials: C
authors.lastname: Seitz
authors.affiliation: Second Department of Urology, Sismanoglio Hospital, Athens Medical School, Athens, Greece.
authors.forename: Andreas
authors.initials: A
authors.lastname: Skolarikos
authors.affiliation: Department of Urology, Technical University Munich, Munich, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Straub
authors.affiliation: Department of Urology, Hospital of the Sisters of Charity, Vienna, Austria.
authors.forename: Christian
authors.initials: C
authors.lastname: Türk
authors.affiliation: Department of Medicine, McMaster University, Hamilton, Canada.
authors.forename: Yuhong
authors.initials: Y
authors.lastname: Yuan
authors.affiliation: Department of Urology, Sindelfingen-Boeblingen Medical Center, University of Tübingen, Sindelfingen, Germany. Electronic address: t.knoll@klinikverbund-suedwest.de.
authors.forename: Thomas
authors.initials: T
authors.lastname: Knoll
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D004867:Equipment Design; D005260:Female; D019983:Guideline Adherence; D006801:Humans; D007223:Infant; D007669:Kidney Calculi / Q000175:diagnosis / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D008904:Miniaturization; D000074642:Nephrolithotomy, Percutaneous / Q000009:adverse effects / Q000295:instrumentation* / Q000592:standards; D017410:Practice Guidelines as Topic / Q000592:standards; D012955:Societies, Medical / Q000592:standards; D013525:Surgical Instruments / Q000592:standards; D016896:Treatment Outcome; D014572:Urology / Q000592:standards*; D055815:Young Adult
keywords: Mini-perc; Percutaneous nephrolithotomy; Residual fragments; Stenting; Stone surgery; Systematic review; Urinary calculi