title: Validity of insertion depth measurement in double-balloon endoscopy.
abstract: OBJECTIVE
  In double-balloon enteroscopy (DBE) the use of a reliable and practical method to calculate the insertion depth of the endoscope could help to improve diagnosis accuracy and optimize the effort and cost of the technique. The objectives of this work were to compare and evaluate two methods of estimating the insertion depth and to obtain a descriptive model capable of representing the exploration dynamics and efficiency in terms of advanced distance and time.
  
  
  METHODS
  Oral DBE was performed in 25 pigs. Insertion depth was calculated during the procedure by: 1) estimation of time and distance for each push and pull cycle during progression; and 2) estimation of distance during withdrawal. At the maximum insertion depth a tattoo was placed, and the observed measures for the two methods were compared with the distance between the pylorus and the mark after euthanasia and necropsy of the animals 1 week after DBE.
  
  
  RESULTS
  The average insertion depth during progression, withdrawal, and after necropsy was 324.92 cm, 317.23 cm, and 342.05 cm, respectively (P Anova = 0.72). The Pearson correlation coefficient (r > 0.85; P < 0.001) and paired Brand - Altman plots demonstrated high agreement between progression and necropsy (0.03 % difference) and between withdrawal and necropsy (6.9 % difference). The exploration dynamics and efficiency in terms of advanced distance per cycle and time fitted to potential and logarithmic regression models, respectively.
  
  
  CONCLUSIONS
  Measurement of insertion depth in vivo was validated in the porcine model during progression and withdrawal. Estimation during progression was more accurate and allowed exploration dynamics and efficiency to be plotted, which might be used as approximate reference values for humans.
authors.affiliation: Anatomy and Comparative Pathology, University of Murcia, Murcia, Spain. albors@um.es
authors.forename: O
authors.initials: O
authors.lastname: López Albors
authors.forename: F
authors.initials: F
authors.lastname: Soria
authors.forename: E
authors.initials: E
authors.lastname: Pérez Cuadrado
authors.forename: E
authors.initials: E
authors.lastname: Morcillo
authors.forename: C
authors.initials: C
authors.lastname: Martín
authors.forename: L F
authors.initials: LF
authors.lastname: Carballo
authors.forename: R
authors.initials: R
authors.lastname: Latorre
mesh_terms: D000818:Animals; D058582:Double-Balloon Enteroscopy / Q000379:methods*; D013552:Swine