title: The Difficult Ureter: Clinical and Radiographic Characteristics Associated With Upper Urinary Tract Access at the Time of Ureteroscopic Stone Treatment.
abstract: OBJECTIVE
  To evaluate the association between clinicoradiographic features and need for prestenting (PS) because of inability of the ureter to accommodate the ureteroscope, or ureteral access sheath, at the time of stone treatment.
  
  
  METHODS
  From 2009 to 2013, 120 consecutive nonstented patients underwent ureteroscopic stone treatment with preoperative computerized tomography urogram. Acute stone events with obstruction or infection were excluded. Preoperative radiographic imaging underwent radiologist review. Clinicoradiographic features were characterized, and multivariable logistic regression models were used to identify covariates independently associated with need for PS.
  
  
  RESULTS
  Of the 154 renal units treated, 25 (16%) required PS for failed primary access. PS ureters were less likely to have a history of prior ipsilateral ureteral stent (4% vs 31%) or surgery (8% vs 36%; P <.05). Radiographically, PS ureters had a narrower ureteropelvic junction (4 mm vs 5 mm) and were more likely to have <50% ureteral opacification on computerized tomography urogram (32% vs 9%; P <.05). On multivariable analysis, prior ipsilateral ureteral stent (odds ratio [OR] = 0.11) and stone surgery (OR = 0.15) reduced the need for PS; meanwhile, <50% ureteral opacification (OR = 4.41) was independently associated with an increased risk of access failure.
  
  
  CONCLUSIONS
  We report a 16% incidence of access failure requiring PS at time of ureteroscopy. Clinically, there was an 89% and 85% risk reduction in the need for PS with prior history of ipsilateral ureteral stent or surgery. Radiographically, there was a 4.4-fold increased risk of PS with <50% ureteral opacification. Accordingly, our findings may assist in counseling and operative management of the difficult ureter.
authors: Department of Urology, Mayo Clinic, Rochester, MN.
authors: Boyd R
authors: BR
authors: Viers
authors: Department of Radiology, Mayo Clinic, Rochester, MN.
authors: Lyndsay D
authors: LD
authors: Viers
authors: Department of Radiology, Mayo Clinic, Rochester, MN.
authors: Nathan C
authors: NC
authors: Hull
authors: Department of Radiology, Mayo Clinic, Rochester, MN.
authors: Theodore J
authors: TJ
authors: Hanson
authors: Division of Health Science Research, Mayo Clinic, Rochester, MN.
authors: Ramila A
authors: RA
authors: Mehta
authors: Division of Health Science Research, Mayo Clinic, Rochester, MN.
authors: Eric J
authors: EJ
authors: Bergstralh
authors: Department of Radiology, Mayo Clinic, Rochester, MN.
authors: Terri J
authors: TJ
authors: Vrtiska
authors: Department of Urology, Mayo Clinic, Rochester, MN. Electronic address: Krambeck.amy@mayo.edu.
authors: Amy E
authors: AE
authors: Krambeck
mesh_terms: D000368:Aged; D015331:Cohort Studies; D016001:Confidence Intervals; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D019060:Minimally Invasive Surgical Procedures / Q000379:methods; D016017:Odds Ratio; D061646:Operative Time; D011300:Preoperative Care / Q000379:methods; D012189:Retrospective Studies; D018570:Risk Assessment; D012720:Severity of Illness Index; D015607:Stents; D014057:Tomography, X-Ray Computed / Q000379:methods; D016896:Treatment Outcome; D014513:Ureter / Q000000981:diagnostic imaging / Q000503:physiopathology; D014514:Ureteral Calculi / Q000000981:diagnostic imaging* / Q000503:physiopathology / Q000601:surgery*; D020709:Ureteroscopes; D018666:Ureteroscopy / Q000379:methods*; D014567:Urography / Q000379:methods