Background: The main disease etiologies requiring emergency high-risk abdominal surgery are intestinal obstruction and perforated viscus and the differences in immune response to these pathologies are largely unexplored. In search of improvement of patient assessment in the perioperative phase, we examined the inflammatory response in this setting, focusing on potential difference in pathophysiology. Methods: The electronic medical records of 487 patients who underwent emergency abdominal surgery from year 2013-2015 for intestinal obstruction and perforated viscus were reviewed. We evaluated the relationship between pre- and postoperative C-reactive protein (CRP) trajectory, fluid balance, and perioperative morbidity and mortality according to type of surgery, intervention, and surgical pathology. Results: A total of 418 patients were included. Pre- and postoperative absolute CRP values were significantly higher in patients with perforated viscus (n = 203) than in intestinal obstruction (n = 215) (P <.0001). Relative changes at hour 6 and POD 1 were non-significant (P =.716 and P =.816 respectively). There was significant association between both pre- (quartile 1 vs 4, OR 5.11; P <.01) and postoperative (quartile 1 vs 4, OR 4.10; P <.001) CRP and adverse outcome, along with fluid balance and adverse outcome in patients with obstruction but not in those with perforation. Fluid balance and CRP had statistically significant positive correlation in patients with obstruction. Conclusions: In this explorative study, a high pre- and postoperative CRP and a high positive fluid balance were associated with worse outcome in patients with intestinal obstruction, but not in patients with perforated viscus. Future studies should address the different inflammatory and fluid trajectories in these specific pathologies.