QS79. Combined Bile and Acid Reflux Produces More Severe Reflux Esophagitis Than Acid Reflux Alone

Introduction: Refluxate in gastro-esophageal reflux disease can be acid only or acid and bile. This has important implications in management of patients as current medical therapy does not address bile reflux. We aim to compare severity and degree of esophagitis in acid alone vs. acid and bile reflux animal models. Methods: Five American Wistar female rats (8-week-old) each in group A (Acid alone) and B (Acid and bile) reflux models were used in this study. In both groups via a midline laparotomy the limiting ridge of the stomach was ligated to render the lower esophageal sphincter incompetent. Additionally in group A the duodenum just beyond the pylorus was covered with a small piece of an 18 Fr suction catheter (width, about 2 mm) to create a partial obstruction model causing increased reflux. In group B the duodenum was covered beyond papilla Vater to cause both bile and acid reflux. The rats were euthanized at three weeks or earlier if clinical deterioration noted. Results: Three week survival rate for group A was 80% (4 of 5) which is significantly higher than 20% (1 of 5) in group B. In group A the rat died due to a perforated esophagus secondary to foreign body ingestion. While in group B three rats died due to of severe reflux esophagitis resulting in perforation on POD #6, #12, and #18 respectively. All rats (10 of 10) had gross and microscopic esophagitis at necropsy. Severe trans-mural necrotic esophagitis was noted in group B while a more subdued esophagitis noted in group A. Conclusion: Both models produce 100% incidence of esophagitis in a reproducible fashion however combined bile and acid reflux cause significantly more severe esophagitis than acid alone. Our next step would be to assess if acid suppression alters this in the combined acid and bile reflux (Group B) model.