Variation Between Observers in Describing Mucosal Appearances in Proctocolitis*

The appearances of the recto-sigmoid mucosa in proctocolitis are so diverse that it is difficult to establish generally applicable and precisely defined descriptive terms. As these appearances are used in diagnosis and as an indication of the course of the disease, it is important that the overall visual impression should be analysed into its various components and that the observer variation in describing them should be known. We have made such an analysis and measured the observer variation in describing each component. As might be expected, we have found that observer-variation for graded characteristics ?for example, shades of red?is high and that for the few discontinuous variables?for example, the presence or absence of blood in the lumen?it is low. Using the best of these criteria, it may be possible to describe mucosal appearances in a more consistent way.