NSAID´s inhibit prostaglandin synthesis 1) decreasing blood flow to the mucosa (mainly by PG subgroups E and I, which promotes vasodilatation), 2) increased adherence of neutrophils, 3) topical irritant effect, 4) impair of the repair/healing process, and 5) gastric-acid-related effects. In a retrospective cohort study, Wilson et al found NSAID´s consumption to correlate with the marginal ulcer development after RYGB. Numerous studies have identified NSAID´s use as a main risk factor for PUD; however, the precise relevance of NSAID´s as a factor in marginal ulcer development after RYGB is largely unknown.