The recent study by Djinbachian et al comparing accuracy of intracolonoscopic to pathology-based assessment of colorectal polyp size is of considerable interest.1 The authors reported that pathology sizing is often not possible because of piecemeal polyp resection or fragmentation during retrieval and, for intact polypectomy specimens, pathology accuracy is limited by formalin-related shrinkage. 78% of pathology-based polyp measurements were smaller than the reference postcolonoscopy size assessed by digital vernier calipre, and mean shrinkage effect was estimated at 25.7%. However, there is another aspect of the pathology assessment which has not been considered and is perhaps a more likely explanation of size reduction based on pathology measurement.

While formalin-related specimen shrinkage is well established, this mainly relates to specimens with significant contractility, such as cutaneous specimens.2 Studies examining the impact of formalin on polyp sizing have yielded conflicting results, though most have suggested …