Utility of Methylene Blue Test in Diagnosis of Early Anastomotic Leaks Post Oncologic Esophagectomy

Abstract

Background: Esophagectomy is currently the best option for treatment of resectable esophageal malignancies. Anastomotic leak (AL) is one of the most devastating post esophagectomy complication carrying high mortality, long hospital stay, poor quality of life. The high mortality is usually due to missed or delay in diagnosis. It is therefore important to make early diagnosis as this will improve outcome. At local hospital, methylene blue dye is often used to assess presence or absence of anastomotic leak prior to initiation of feeding. However, reports indicate that in a significant number of patients, the leaks occur despite a negative methylene blue dye test. Study objective: To determine the accuracy of methylene blue dye test in diagnosis of early anastomotic leaks post oncologic esophagectomy in Kenyatta National Hospital Methodology: A 6 year a retrospective analytical study of 265 patients who underwent esophagectomy at KNH between January 2017 and January 2023 for esophageal cancer and had methylene blue test done before post-operative day 10 was performed. . Data was collected via consecutive sampling .Of particular interest was findings of methylene blue dye test and clinical confirmation of anastomotic leak: characteristic chest drain effluent, leakage of digestive fluids; saliva and bile, food particles, pus from the cervical incision site. Results: Out of 265 patients who were analysed, 29.45% (n=78) had clinical anastomotic leak 4.2% (n=11) patients had a positive methylene blue dye test and 95.8% (n=254) had a negative test. Sensitivity and specificity of MB test was found to be 14.1 and 100% respectively with positive predictive and negative predictive values of 100% and 73.6% viii respectively. 93.6% (n=73) of the patients who had AL had their anastomosis on the cervical region, while 6.4% (n=5) had intrathoracic anastomosis. Majority of the patients who had positive test had the test done on day 5 and 6. Mean and median post-operative day when methylene blue test was carried out was found to be day 7, standard deviation of 0.8. Most common clinical features of EAL were leakage of ingested food particles and pus drainage from incision site. AL was found to occur mostly on post-operative day 10 in KNH. Conclusion Methylene blue test has high specificity but very low sensitivity, making it ideal to be used as a screening test, other test should be done to confirm diagnosis