The following Critically-Ill patients have a significant increased risk of stress-related mucosal disease (SRMD): 1) mechanical ventilation > 48hrs conveys a 16-fold risk (p < 0.001), 2) coagulopathy has a 4-fold risk (p < 0.001), 3) shock carries a 3.7-fold risk (p= 0.08), 4) drop of intramural pH (from 8 to 6, 5), 5) increase of the number of risk factors (from 0 to 4), 6) recent major surgery, 7) major trauma, 8) severe burns, 9) head trauma, 10) hepatic or renal disease at admission, and 11) sepsis. SRMD encompasses stress-related injury (SRI), which is primarily erosion in the GI tract, and stress ulcer, which is a focal deep mucosal damage. The pathogenesis of SRMD has not being unraveled completely but there is strong evidence that hypoperfusion and reperfusion of the upper GI tract is the major cause. There is no literature available about marginal ulcer after RYGB associated to ICU or critically ill patients.