interval (CI) 0.19 to 2.12), with limits of agreement from -2.78 to 3.58 cm. For M, the mean difference between pull and push endoscopy was 0.77 cm (95% CI -0.19 to 2.18), with limits of agreement from -2.33 to 3.86 cm. The mean difference in C between doctor and nurse was -0.17 cm (95% CI -0.92 to 2.77), with limits of agreement from -4.20 to 3.87 cm. For M the mean difference between doctor and nurse was -0.63 cm (95% CI -1.35 to 2.63), with limits of agreement from -4.47 to 3.21 cm. Conclusions: The correlation coefficients for pull against push endoscopy and doctor against nurse demonstrate the strong relationship between these variables. However, there were considerable discrepancies between C & M values in both comparisons, with wide limits of agreement. Possible explanations for a reduced level of agreement in this real-time clinical setting include: patient movement and retching, differences in landmark interpretation and measurement technique, and the lack of 1 cm markings on the endoscope.