Background Chylous ascites is often reported in cases with lymphatic obstruction or after lymphatic injuries such as intraabdominal malignancies or lymphadenectomies. However, chylous ascites is also frequently encountered in operations for internal hernias. We sought to characterize the frequency and conditions when chylous ascites is encountered in general surgery patients. MethodsData from patients who underwent operations for CPT codes related to open and laparoscopic abdominal and gastrointestinal surgery in our tertiary hospital from 2010 to 2019 were reviewed. Patients with the postoperative diagnosis of internal hernia were identified and categorized into three groups: Internal Hernia with chylous ascites, non-chylous ascites, and no ascites. Demographics, prior surgical history, CT findings, source of internal hernia, open or laparoscopic surgery, and preoperative labs were recorded and compared. ResultsFifty-six patients were found to have internal hernias and were included in our study. 80.3% were female and 86% had a previous Roux-en-Y gastric bypass procedure (RYGBP).Laparoscopy was the main approach for all groups. Ascites was present in 46% of the cases. Specifically, chylous ascites was observed in 27% of the total operations and was exclusively (100%) found in patients with gastric-bypass history. Furthermore, it was more commonly associated with Petersen's defect (p<0.001), while the non-chylous fluid group was associated with herniation through the mesenteric defect (p<0.001).Conclusions Chylous ascites is a common finding during internal hernia operations. Unlike other more morbid conditions, identification of chylous ascites during an internal hernia operation appears innocuous. However, in the context of a patient with a history of RYGBP, the presence of chylous fluid signifies the associated small bowel obstruction is likely related to an internal hernia through a patent Petersen's defect.