Background and Aims Intestinal obstruction is a common acute abdominal condition, and early diagnosis and timely surgical intervention are critical to patient prognosis. After radical gastrectomy for gastric cancer, due to abnormal digestive tract reconstruction, mesenteric space formation, and peritoneal injury, the incidence of intestinal obstruction is relatively high, often accompanied by ascites of varying characteristics. Bloody ascites usually suggest intestinal wall ischemia and necrosis; however, current clinical indicators have limited effectiveness in the early identification of this condition. This study was performed to investigate the clinical characteristics of postoperative small bowel obstruction with different types, with a particular focus on identifying markers with diagnostic values for bloody ascites.Methods The clinical data of 65 patients with small bowel obstruction and ascites after radical gastrectomy for gastric cancer admitted to the Department of Gastrointestinal Surgery of Jiangyin People's Hospital between January 2010 and December 2021 were retrospectively analyzed. Based on the ascites characteristics, patients were divided into serous ascites group (n=42), chylous ascites group (n=9), and bloody ascites group (n=14). Clinical parameters and preoperative white blood cell count (WBC), neutrophil count (NEU), lymphocyte count, and neutrophil-to-lymphocyte ratio (NLR) were compared among the groups. Receiver operating characteristic (ROC) curve analysis was used to evaluate the diagnostic value of inflammatory markers for bloody ascites.Results The time from onset to hospital admission was significantly longer in the serous ascites group compared to the chylous and bloody ascites groups (P<0.05). Postoperative hospital stay was significantly prolonged in the bloody ascites group compared to the other two groups (P<0.05). The rate of small bowel resection in the bloody ascites group (6/14) was significantly higher than that in the chylous ascites group (0/9) or serous ascites group (7/42) (P<0.05). Although the recurrence rate in the bloody ascites group (3/14) was higher than in the chylous ascites group (1/9) or serous (2/42) ascites group, the difference was not statistically significant (P>0.05). WBC, NEU, and NLR levels increased progressively from the serous to chylous to bloody ascites groups, with statistically significant differences (P<0.05). ROC curve analysis showed that NLR had superior diagnostic performance in predicting bloody ascites (AUC: 0.84; sensitivity: 75%; specificity: 85%) compared to WBC and NEU.Conclusion NLR is closely associated with the characteristics of ascites in patients with small bowel obstruction after radical gastrectomy and is significantly elevated in those with bloody ascites. Compared to traditional inflammatory markers WBC and NEU, NLR demonstrates higher sensitivity and specificity for identifying bloody ascites, making it a valuable adjunct diagnostic tool for predicting intestinal wall ischemia and necrosis. Furthermore, patients with bloody ascites showed higher rates of bowel resection and more extended hospital stays, suggesting a poorer clinical prognosis.