Accuracy of measurements of the length of esophageal lesions: An experimental study

Background and study aims: Hiatal hernia, Barrett's esophagus and erosive esophagitis are defined and classified by measuring their length during endoscopy. The primary aim of our study was to evaluate the accuracy of length measurement of esophageal lesions with the conventional gastroscope marked at 5-cm intervals, and the secondary aim was to test the performance of a modified gastroscope marked at 1-cm intervals. Methods: 24 senior endoscopists carried out endoscopy on a plastic mannequin. The esophagus was randomly replaced by one of a set of seven plastic tubes, each tube having two colored rings which were 1,1.5, 2, 2.5, 3, 3.5 or 4 cm apart. The endoscopists were asked to measure the distance between the mouth-guard and each of the two "esophageal" rings during endoscope withdrawal, with a precision of 0.5 cm. All participants endoscoped all seven tubes blindly, first using the conventional scope and then the modified scope. Results: Using the conventional gastroscope, measurements were overall incorrect in 67.9% (95% Cl 61-75.1) of cases and incorrect by at least 1 cm in 21% (95% Cl 14.8-27.2) of cases. These percentages were significantly reduced by using the modified gastroscope (47.6%, 95% Cl 40.1 - 55.2 and 7.1 %, 95 % CI 3.2 -11.0, respectively) (P <0.001). Overall accuracies in measuring lengths of ≥ 2 cm and ≥ 3cm, corresponding to hiatal hernia and Barrett's esophagus definitions, were 83% and 94%-95% with the conventional and modified gastroscopes, respectively (P <0.05). Conclusions: Our data suggest that estimation of the length of esophageal lesions using conventional endoscopes is inaccurate. The accuracy of measurements is significantly improved with the use of an endoscope marked at intervals of 1 cm.