title: Kinking of the upper ureter in CT urography: anatomic and clinical significance.
abstract: OBJECTIVE
  Although the course of the ureter is described as a straight descent in the retroperitoneum, kinking of the upper ureter is often seen at imaging. The aim of this study was to investigate kinking of the ureter and its underlying anatomico-clinical significance.
  
  
  METHODS
  We evaluated 176 computed tomography (CT) images and classified kinking into three grades: no/mild kinking as Grade 1, moderate as Grade 2, and severe as Grade 3. We defined the "crossing point" (CP) as where the ureter crosses over the gonadal vein and assessed its relation to the kinking. Fourteen halves from seven cadavers were used for examination. Approaching anteriorly, we macroscopically observed the ureter and surrounding structures.
  
  
  RESULTS
  On CT, the rate of the radiologically "significant" kinking classified into either Grade 2 or 3 was 18.4 % on the right and 21.8 % on the left. All kinking was either at or above the level of the CP. In cadavers, the ureter was relatively mobile in the perirenal fat and then beginning at approximately the level of the CP became firmly fixed to the anteromedial aspect of the psoas major muscle.
  
  
  CONCLUSIONS
  Kinking of the upper ureter is not a clinically significant finding and arises from the ureter having a relatively mobile portion in the perirenal space compared to its caudal portion. The fixation boundary can be identified by observing the CP.
authors.affiliation: Department of Radiology, St. Luke's International Hospital, 9-1 Akashi-cho, Chuo-ku, Tokyo, 104-8560, Japan.|Department of Radiology, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo, 113-8519, Japan.
authors.forename: Minobu
authors.initials: M
authors.lastname: Kamo
authors.affiliation: Department of Radiology, St. Luke's International Hospital, 9-1 Akashi-cho, Chuo-ku, Tokyo, 104-8560, Japan.
authors.forename: Taiki
authors.initials: T
authors.lastname: Nozaki
authors.affiliation: Department of Clinical Anatomy, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo, 113-8519, Japan.
authors.forename: Kyoko
authors.initials: K
authors.lastname: Yoshida
authors.affiliation: Department of Radiology, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo, 113-8519, Japan.
authors.forename: Ukihide
authors.initials: U
authors.lastname: Tateishi
authors.affiliation: Department of Clinical Anatomy, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo, 113-8519, Japan. akita.fana@tmd.ac.jp.
authors.forename: Keiichi
authors.initials: K
authors.lastname: Akita
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002102:Cadaver; D004210:Dissection; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016658:Psoas Muscles / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D011860:Radiography, Abdominal; D012187:Retroperitoneal Space; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed; D014513:Ureter / Q000000981:diagnostic imaging* / Q000473:pathology*; D014514:Ureteral Calculi / Q000209:etiology; D014517:Ureteral Obstruction / Q000209:etiology; D053039:Ureterolithiasis / Q000150:complications; D014567:Urography; D055815:Young Adult
keywords: CT urography; Psoas fascia; Radiological anatomy; Renal fascia; Ureter