Gastric Distension Index: A Novel Radiographic Marker Associated With Postoperative Gastric Stasis After Gastrectomy.

Background: Gastric remnant distension after gastrectomy is associated with gastrointestinal symptoms and poor postoperative outcomes, particularly in elderly patients. However, no objective clinical index has been established to define or predict this condition. Methods: We retrospectively analyzed 67 patients who underwent distal gastrectomy (DG) in 2019 with upright abdominal X-ray imaging. Radiographic indices were evaluated for their association with gastrointestinal symptoms and the need for intervention for postoperative gastric stasis. The maximum width of the gastric bubble was the most predictive and standardized into the Hiki Index (HI). A cutoff value was determined from ROC analysis based on stasis-related intervention. Validation was performed in a prospectively collected cohort of 136 patients who underwent DG or pylorus-preserving gastrectomy (PPG) between 2022 and 2023 after clinical implementation of the HI. Results: In the test set, HI showed high predictive accuracy for stasis-related intervention (AUC 0.78, sensitivity 85.7%, specificity 76.7%). In the validation set, HI predicted symptoms such as nausea (AUC 0.77), bloating (0.77), and belching (0.90). HI-based gastric distension was not associated with postoperative complications. Age < 75 years (OR 3.29), female sex (OR 2.58), and undergoing PPG (OR 6.21) were identified as independent risk factors for gastric distension. Conclusion: The HI is a reproducible and practical radiographic indicator for identifying patients at risk of postoperative gastric stasis and related symptoms. Its use may facilitate early intervention and improve postoperative care. Prospective implementation of the HI contributed to more consistent symptom documentation and clearer associations between HI and gastrointestinal symptoms.