Profound spatial clustering of simultaneous peptic ulcers.

In an endoscopic study of 90 consecutive patients with more than one peptic ulcer, the ulcers in an individual were profoundly spatially clustered. Clustering of ulcer locations was shown using a non-parametric test of clustering (Kruskal-Wallis statistic with 89 degrees of freedom = 151.31, probability of observing this extreme statistic with no clustering less than 0.0005) and a parametric test of clustering (F test statistic with 89 and 124 degrees of freedom = 5.41, probability of observing this extreme statistic with no clustering less than 0.0005). Patients having their largest ulcer in any given region had a much greater likelihood than other patients of having other ulcers in that same site. For example, the 26 patients with their largest ulcer in the proximal duodenal bulb had 20 of 33, or 61% (9) (standard error), of their other ulcers in the proximal duodenal bulb. In contrast, the 18 patients with their largest ulcer in the proximal stomach had four of 23, or 17% (8), of their other ulcers in the proximal duodenal bulb. Of the 59 patients who had two simultaneous ulcers, 28 patients had adjacent ulcers (distance between ulcers less than 4% of the distance from the gastric cardia to the apex of the duodenal bulb). These findings suggest that local factors may be important in the pathogenesis of simultaneous peptic ulcers, including infection caused by Campylobacter pylori or other microorganisms, ischaemia and mucosal barrier disruption.