title: Prospective determination of ureteral orifice location: a guide for fluoroscopic ureteral stent insertion.
abstract: OBJECTIVE
  Ureteral stents are commonly inserted under fluoroscopic guidance. Our objective was to determine the intravesical landmarks for stent insertion by mapping the fluoroscopic location of the ureteral orifices (UOs) and bladder neck (BN) in relation to the pubic symphysis (PS).
  
  
  METHODS
  In patients undergoing ureteroscopy, the UO to BN distance was measured during cystoscopy with a 5F ureteral catheter. Radiographic distance between the UO, BN, and superior border of the PS was determined by mapping their locations on digital fluoroscopic images. Measurements were performed with a full (to 50 cm H2O) and empty bladder.
  
  
  RESULTS
  With an empty bladder, the mean cystoscopic BN to UO distance was 1.8 cm (+/- 0.4) for men (n = 10) and 2.0 cm (+/- 0.4) for women (n = 11). With a full bladder, it was 2.8 cm (+/- 0.5) for men and 2.9 cm (+/- 0.6) for women. Although the intravesical distance lengthened during cystoscopy (by 50%), there was no difference when viewed fluoroscopically; the BN to UO distance lengthened by only 15%. In men, the UOs were located superior to PS in the majority (83% and 95%, empty and full bladder, respectively). In women, however, the UOs resided behind the PS (73% and 50%, empty and full bladder, respectively). The BN in men was also cephalad to that in women (P = 0.01); superior to the PS in 50%; and behind the upper two thirds of the PS in 50%. In women, the BN was behind the lower two thirds of the PS in the majority (81%).
  
  
  CONCLUSIONS
  During fluoroscopic ureteral stent insertion, the radiopaque marker of the stent positioner is situated at the superior border of the PS in men and behind the lower one third of the PS in women, permitting formation of an intravesical distal coil. One way to remember this is that men are on top and women are on the bottom of the PS.
authors.affiliation: Department of Urology, University of Toronto, Toronto, British Columbia, Canada. alixperks@hotmail.com
authors.forename: Alexandra E
authors.initials: AE
authors.lastname: Perks
authors.forename: Trevor D
authors.initials: TD
authors.lastname: Schuler
authors.forename: Kenneth
authors.initials: K
authors.lastname: Pace
authors.forename: R John
authors.initials: RJ
authors.lastname: Honey
mesh_terms: D005260:Female; D005471:Fluoroscopy; D006801:Humans; D008297:Male; D008875:Middle Aged; D012727:Sex Characteristics; D015607:Stents; D014513:Ureter / Q000000981:diagnostic imaging*; D001743:Urinary Bladder / Q000000981:diagnostic imaging