Finding mucosal tears in collagenous colitis during colonoscopic insufflation

Recently, I had the opportunity to review the interesting retrospective descriptive study of Cruz-Correa et al (Gut 2002;51:600). In brief, the authors described three patients who underwent colonoscopic examination for evaluation of chronic diarrhoea. During the colonoscopic examination, prominent mucosal tears in the ascending and transverse colon regions were noted. Biopsies of macroscopically normal appearing mucosa revealed changes supportive of underlying collagenous colitis. The authors attributed the mucosal tears, and their distribution, to the collagenous colitic process.

I have wondered about another possibility. Although the examinations were performed by experienced endoscopists, could these lesions have been induced by barotrauma? Along these lines, were the lacerations seen as the colonoscope was actually in the ascending colon and insufflation was performed, or were they found “unexpectedly” as the proximal colon was intubated, as has been reported in barotrauma induced colon lacerations.¹ Barotrauma induced colon injury can obviously occur when even an experienced endoscopist has performed the colonoscopic examination. Furthermore, the authors suggest that the distribution of the lacerations correlated with the distribution where one usually documents the “thickest” collagen tables—in the proximal colon. Could the distribution of these lacerations been related not to the thickness of the subepithelial collagen table but to the diameter of the colon where the lacerations were noted, being found where the colon is usually of greatest diameter? The diameter of the colon is usually greatest in the caecal and ascending colon regions. According to Laplace’s law, the tension on the wall of a cylindrical vessel is proportional to its radius. It is therefore most likely that barotrauma induced lacerations would be found in the proximal colon, regardless of where the “thickest” subepithelial collagen deposition might be found.

In summary, I would be interested in the authors’ opinions regarding the hypothesis that the findings they described might be related to barotrauma, as opposed to the underlying collagenous colitic process. The authors are correct that similar lesions have not been reported in other gastrointestinal diseases but have been described in patients undergoing colonoscopy and, at the least, they are certainly not specific for the presence of underlying collagenous colitis.