title: Preoperative assessment of the ureter with dual-phase contrast-enhanced computed tomography for lateral lumbar interbody fusion procedures.
abstract: BACKGROUND
  Performing the minimally invasive lateral lumbar interbody fusion (LIF), such as the extreme lateral interbody fusion (XLIF) and oblique lateral interbody fusion (OLIF), through a retroperitoneal approach has become increasingly popular. Although urological injury is a major complication of LIF, the anatomical location of the ureter and its risk of injury have not been assessed. The purpose of this study was to evaluate the efficacy of dual-phase contrast-enhanced computed tomography for assessing the location of the ureter and risk of its injury in consecutive LIF cases.
  
  
  METHODS
  27 cases (12 men and 15 women) were enrolled in the study. Dual-phase contrast-enhanced CT was performed preoperatively, and the risk of ureteral injury was assessed. The location of the ureter was classified using the psoas muscle and vertebral body as reference structures for OLIF and XLIF procedures, respectively. During the OLIF procedures, the location of the ureter was additionally assessed with direct vision and manual palpation in all cases. Simultaneously, potential vascular anomalies were assessed with both 3D and axial images of CT.
  
  
  RESULTS
  A total of 125 among 162 ureters, excluding 13 with insufficient enhancement and 24 (44.4%) within the kidney at the L2-L3 level, were assessed preoperatively; 113 ureters (90.4%) were classified as anatomically close to the surgical corridor for OLIF, and 20 ureters (16.0%) as having a potential risk of injury during XLIF. In one case, OLIF was converted to a conventional posterior procedure because of a vascular anomaly. Intraoperative findings showed that ureters moved anteriorly with the peritoneum in all cases, as assessed by manual palpation under direct vision.
  
  
  CONCLUSIONS
  Dual-phase contrast-enhanced CT is useful in assessing the location of the ureter, kidney, and vascular structures simultaneously. Both OLIF and XLIF have a potential risk of urological injury.
authors.affiliation: Department of Orthopaedic Surgery, Graduate School of Medicine, Kyoto University, 54 Shogoin Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan. Electronic address: shfuji@kuhp.kyoto-u.ac.jp.
authors.forename: Shunsuke
authors.initials: S
authors.lastname: Fujibayashi
authors.affiliation: Department of Orthopaedic Surgery, Graduate School of Medicine, Kyoto University, 54 Shogoin Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan.
authors.forename: Bungo
authors.initials: B
authors.lastname: Otsuki
authors.affiliation: Department of Orthopaedic Surgery, Graduate School of Medicine, Kyoto University, 54 Shogoin Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Kimura
authors.affiliation: Department of Orthopaedic Surgery, Graduate School of Medicine, Kyoto University, 54 Shogoin Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan.
authors.forename: Shimei
authors.initials: S
authors.lastname: Tanida
authors.affiliation: Department of Orthopaedic Surgery, Graduate School of Medicine, Kyoto University, 54 Shogoin Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan.
authors.forename: Kazutaka
authors.initials: K
authors.lastname: Masamoto
authors.affiliation: Department of Orthopaedic Surgery, Graduate School of Medicine, Kyoto University, 54 Shogoin Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan.
authors.forename: Shuichi
authors.initials: S
authors.lastname: Matsuda
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D003287:Contrast Media / Q000008:administration & dosage; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D007275:Injections, Intravenous; D007431:Intraoperative Complications / Q000517:prevention & control*; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D019060:Minimally Invasive Surgical Procedures / Q000379:methods*; D061330:Multidetector Computed Tomography / Q000379:methods*; D057234:Preoperative Period; D015203:Reproducibility of Results; D013123:Spinal Fusion / Q000379:methods*; D014513:Ureter / Q000000981:diagnostic imaging* / Q000293:injuries; D014570:Urologic Diseases / Q000209:etiology / Q000517:prevention & control*
chemical_list: D003287:Contrast Media