Safety of Delayed Operation for Small Bowel Obstruction: Nationwide Real-World Data Analysis

Nonoperative management (NOM) is widely used for uncomplicated small bowel obstruction, but failure of NOM may lead to adverse outcomes. The optimal duration of NOM before surgery remains unclear. This study aimed to identify a safe time window for NOM using a nationwide real-world dataset in Japan.

We performed a retrospective cohort study using the Japanese Diagnosis Procedure Combination database, including 11,034 adult patients who underwent surgery for small bowel obstruction between 2016 and 2020. Patients were grouped based on the number of days from admission to surgery: 0 to 3 (group 1), 4 to 7 (group 2), 8 to 13 (group 3), and 14 to 28 days (group 4). Multivariate logistic regression assessed the association between surgical timing and outcomes.

There was no significant difference in the reoperation rate requiring general anesthesia (group 2; p = 0.654, group 3; p = 0.415, group 4; p = 0.708) or in-hospital mortality rate (group 2; p = 0.074, group 3; p = 0.529, group 4; p = 0.695) between groups. The bowel resection rate was significantly higher in groups 2 to 4 compared with group 1 (odds ratio 1.53, 2.08, 2.19; p < 0.001). Aspiration pneumonia was significantly more frequent in group 4 (odds ratio 1.74; p < 0.001). Reoperation and in-hospital mortality rates did not differ significantly between groups. Fatal cases had higher pneumonia and transfusion rates but lower bowel resection rates, suggesting perioperative condition rather than surgical timing may influence mortality.

Extending NOM beyond 3 days increases the risk of bowel resection and beyond 14 days raises the risk of aspiration pneumonia. These findings support early surgical consideration.