<prompt> A posteriorly perforating ulcer in the pyloric antrum of the stomach is most likely to produce initial localized peritonitis or abscess formation in the following:Omental bursa lesser sacGreater sacRight subphrenic spaceHepato renal space pouch of Morison  <response>: Answer is A Omentum bursa Gastric ulcers perforate into the lesser sac, which can be paicularly difficult to diagnose - Bailey A gastric ulcer perforates into the lesser sac, then no signs of generalised peritonitis can be seen but misleading symptoms may appear - Schwaz As can be seen from the figure, a posteriorly perforating ulcer of the stomach will localize in the lesser sac or omental bursa only. lesser sacis synonymous with omental bursa 