title: X-ray-free Ultrasound-guided Percutaneous Nephrolithotomy: How to Select the Right Patient?
abstract: OBJECTIVE
  To identify factors associated with successful ultrasound guidance for each surgical step of ultrasound-guided percutaneous nephrolithotomy (PCNL).
  
  
  METHODS
  Consecutive patients undergoing PCNL between March 2015 and June 2016 were prospectively enrolled. An attempt was made to use ultrasound guidance in renal access, tract dilation, and nephrostomy tube placement for each patient. For steps during which ultrasound guidance was unsuccessful, fluoroscopic screening was applied. Regression analysis identified patient characteristics associated with successful use of ultrasound guidance.
  
  
  RESULTS
  A total of 96 patients composed this cohort, with a mean body mass index of 28.7 kg/m2. Mean stone size was 33.1 ± 18.9 mm, and no hydronephrosis was found in 63.5% of cases. Fluoroscopic screening was required for renal access in 27 cases (28.1%), tract dilation in 38 (39.6%), and nephrostomy tube placement in 80 (83.3%). Multivariate analysis demonstrated that successful ultrasound guidance was significantly associated with the presence of hydronephrosis for renal access and the absence of staghorn calculi for tract dilation. Ultrasound-guided nephrostomy tube placement appeared linked to surgeon experience.
  
  
  CONCLUSIONS
  To achieve completely x-ray-free ultrasound-guided PCNL, the ideal patient should have a hydronephrotic collecting system with no staghorn stone present. For practitioners looking to adopt ultrasound guidance into their PCNL practice, these represent the most appropriate patients to safely initiate a surgical experience.
authors.affiliation: Department of Urology, University of California, San Francisco, San Francisco, CA; Division of Urology, Faculty of Medicine, Chulalongkorn University, King Chulalongkorn Memorial Hospital, The Thai Red Cross Society, Rama IV Road, Patumwan, Bangkok, Thailand.
authors.forename: Manint
authors.initials: M
authors.lastname: Usawachintachit
authors.affiliation: Department of Urology, University of California, San Francisco, San Francisco, CA.
authors.forename: David T
authors.initials: DT
authors.lastname: Tzou
authors.affiliation: Department of Urology, Tsinghua Changgung Hospital, Beijing, China.
authors.forename: Weiguo
authors.initials: W
authors.lastname: Hu
authors.affiliation: Department of Urology, Tsinghua Changgung Hospital, Beijing, China.
authors.forename: Jianxing
authors.initials: J
authors.lastname: Li
authors.affiliation: Department of Urology, University of California, San Francisco, San Francisco, CA. Electronic address: Tom.Chi@ucsf.edu.
authors.forename: Thomas
authors.initials: T
authors.lastname: Chi
mesh_terms: D000328:Adult; D000368:Aged; D004106:Dilatation; D005260:Female; D005471:Fluoroscopy; D006801:Humans; D006869:Hydronephrosis / Q000150:complications / Q000000981:diagnostic imaging / Q000601:surgery; D007669:Kidney Calculi / Q000150:complications / Q000000981:diagnostic imaging* / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D000074642:Nephrolithotomy, Percutaneous; D018579:Patient Selection; D011446:Prospective Studies; D025321:Surgery, Computer-Assisted; D014463:Ultrasonography