Development and internal validation of the Operate-Now Score for early prediction of clinically significant intestinal ischemia in adhesive small bowel obstruction.

BACKGROUND: Adhesive small bowel obstruction (ASBO) is the leading cause of mechanical small bowel obstruction in developed countries and represents a major burden in emergency surgery. Early identification of clinically significant intestinal ischemia remains challenging. Delayed surgical intervention increases the risk of bowel resection and postoperative morbidity. This study aimed to develop and internally validate a simplified clinical-radiological score for early prediction of intestinal ischemia requiring resection. METHODS: A retrospective single-center observational study was conducted including 236 consecutive adult patients admitted with mechanical small bowel obstruction between 2020 and 2024. The primary endpoint was intestinal resection, used as a proxy for clinically significant ischemia. Independent predictors were identified using multivariate logistic regression. Model discrimination was assessed using ROC curve analysis and area under the curve (AUC). Internal validation was performed using bootstrap resampling (1000 iterations). RESULTS: Sixty-three patients (26.7%) required intestinal resection. Independent predictors of resection were serum lactate (OR 4.14 per 1 mmol/L increase; 95% CI 2.42-7.10; P<0.001), CT wall hypoenhancement (OR 3.39; 95% CI 1.47-7.78; P=0.004), and intraperitoneal free fluid (OR 4.07; 95% CI 1.56-10.66; P=0.004). The final model demonstrated good discrimination (AUC 0.839) with optimism-corrected AUC of 0.810. CONCLUSIONS: The Operate-Now Score integrates metabolic and radiological parameters to support early identification of ASBO patients at high risk of ischemia. External prospective validation is required before widespread implementation.