Abstract Background Fundoplication is one of the common surgical procedures offered to patients who have not responded to medical or conservative treatment for Gastroesophageal-Reflux-Disease.Within our trust routine-PH manometry,barium swallow and OGD are preferred pre-op investigations.According to the guidelines set forth by SAGES(Society of American Gastrointestinal and Endoscopic Surgeons)-PH manometry and endoscopy are recommended as the preferred methods for pre-operative assessment.PH manometry is considered the gold standard for detecting reflux and dysmotility.Our objective is to evaluate and compare the local practice with published literature on identifying the accuracy of pre-operative barium swallow and ph manometry in diagnosing reflux and dysmotility. Methods A retrospective review of electronic medical records of patients who had Nissen fundoplication at Ealing Hospital between January2017-December2022 was included in the study. Among these, patients who had both pre-operative assessments - barium swallow and Ph manometry were included in the cohort. Initial data was retrieved from the Surgical operating service list and was further analyzed with the help of EPRO ( Electronic information provider) for information on Barium swallow, Ph manometry studies, and postoperative outcome. Results In a study of 54 Nissen Fundoplication patients (mean age M&F 58), 25 underwent pH manometry and barium swallow- Concordant positive results were found in 13 patients (52%), indicating reflux. Discordant results occurred in 11 patients (44%) with positive manometry but negative barium swallow, favoring pH manometry's sensitivity. Of the 25 patients analyzed, 20 (80%) had good symptom control, while 3 (12%) experienced symptom recurrence, and 2 (8%) missed follow-ups. Barium swallow missed 8 dysmotility cases, while pH manometry missed 4. Among 46 patients with detected hiatus hernia by OGD, only 26 (54%) were accurately diagnosed using barium swallow. Conclusions Our study demonstrated that Ph manometry is a reliable pre-operative assessment tool for anti-reflux surgery, achieving 100% accuracy in detecting reflux compared to only 55% accuracy with barium swallow. With dysmotility, Ph manometry showed better results of 67% whereas barium swallow identified only 33%. Barium swallow should be used as an additional investigation for failed pH studies and reflux-related dysphagia symptoms. It can also be valuable in post-operative cases to evaluate wrap position and potential complications due to tightness. These findings were presented at the local surgical audit meeting, and future cycles will focus on guideline compliance assessment.