title: Colon anatomy based on CT colonography and fluoroscopy: impact on looping, straightening and ancillary manoeuvres in colonoscopy.
abstract: BACKGROUND
  Unsedated colonoscopy is an uncomfortable procedure for most patients. Discomfort during colonoscopy is largely related to looping of the colonoscope which displaces the colon from its native configuration. Therefore, complete intubation of the colon is considerably difficult in up to 10-20% of procedures. Aims of this study were to determine the "normal" colon anatomy in CT-colonoscopy with special focus on length, number of flexures and tortuosity and to assess frequency and type of looping as well as straightening manoeuvres based on fluoroscopic findings.
  
  
  METHODS
  100 consecutive screening patients underwent CT colonography and another 100 cases traditional colonoscopy with fluoroscopic aid. Interactive 3D colon maps and 2D MPR images from virtual procedures were reviewed by two experienced GI-radiologists and GI-endoscopists. Colonoscopy was performed by three board-certified gastroenterologists. Fluoroscopic films of each case were recorded and retrospectively analysed.
  
  
  RESULTS
  There was a considerable difference in overall colonic length between CT colonography and conventional colonoscopy (167 cm vs. 93.5 cm). Number of acute angle flexures and degree of tortuosity was higher in CT colonography than previously assumed. The caecum was reached in 98/100 cases with conventional colonoscopy. Procedures were incomplete due to an obstructing sigmoid cancer and a floppy redundant colon. Looping occurred in 73/100 cases and straightening manoeuvres with fluoroscopy were highly effective in 95%. Looping was more common in older and smaller women.
  
  
  CONCLUSIONS
  Predictive anatomical factors for potentially difficult endoscopic colonoscopy can be defined by CT colonography. Looping occurs frequently during routine colonoscopy but hindered caecal intubation in only one case. Short-term fluoroscopy is extremely helpful to guide straightening and ancillary manoeuvres and should be used selectively in patients with looping during conventional colonoscopy.
authors.affiliation: Medical Department C, Klinikum Ludwigshafen gGmbH, Department of Interdisciplinary Endoscopy, University Hamburg-Eppendorf, Martinistrasse 52, Hamburg, Germany. a.eickhoff@uke.uni-hamburg.de
authors.forename: Axel
authors.initials: A
authors.lastname: Eickhoff
authors.forename: Perry J
authors.initials: PJ
authors.lastname: Pickhardt
authors.forename: Dirk
authors.initials: D
authors.lastname: Hartmann
authors.forename: Jürgen F
authors.initials: JF
authors.lastname: Riemann
mesh_terms: D003106:Colon / Q000033:anatomy & histology* / Q000000981:diagnostic imaging*; D003113:Colonoscopy / Q000379:methods*; D005260:Female; D005471:Fluoroscopy; D006801:Humans; D008297:Male; D008875:Middle Aged; D014057:Tomography, X-Ray Computed