Purpose To evaluate whether common bowel-related CT signs alone can reliably identify irreversible bowel injury in acute mesenteric ischemia (AMI) and to develop a radiological score to enhance reporting and assist clinical decision-making. Methods This ancillary analysis of the multicentre AMESI study included 157 patients with suspected or confirmed AMI from 11 international sites. Predefined bowel-related CT signs were retrospectively assessed by two independent radiologists, blinded to clinical data. Predictive scores for irreversible bowel injury (transmural necrosis) and AMI of any severity, as confirmed by clinical outcomes, were constructed and tested using regression models. Results The final score, optimized for arterial occlusive AMI, classified patients as high-risk for irreversible injury if either decreased/absent bowel wall enhancement or pneumatosis intestinalis (each giving 2 points) was present, or if two of the following were observed (each giving 1 point): bowel dilatation, portal/mesenteric venous gas, or paper-thin bowel wall. Using a cut-off of ≥ 2 points, the score correctly identified irreversible damage in 62 of 80 patients, the overall accuracy was 70%. Sensitivity analysis using histologically confirmed transmural necrosis showed comparable performance. In most of the false negative cases (n = 18, five of them with no signs), time from CT to confirmed necrosis was > 6 h. No single score could distinguish reliably between three categories: no AMI, reversible, and irreversible injury. Conclusions The AMESI CT-score, developed in this study demonstrated moderate accuracy in identifying irreversible bowel injury. External validation is required to determine its potential utility in clinical decision-making, particularly in triaging AMI patients for surgical versus endovascular treatment. Clinical trials registration NCT06445660.