How to Create the “Blue Dye” for the Submucosal Cushion

How to Prepare the Blue Dye for Submucosal Injection

Preparing the blue-colored submucosal injection solution is an important step for advanced endoscopic resections. An adequate submucosal cushion is useful to show flat lesions, highlight shoulder borders, and delineate the extent of the lesion. It provides a cushion of safety that reduces the chances of resection with perforation. Delineating these borders helps improve the vertical and lateral margins during R0 resection. Using a color mixture is the basis of interventional chromoendoscopy.

Selecting the Right Contrast Agent

Several blue contrast agents are available, including indigo carmine, methylene blue, and toluidine blue. The best substance for endoscopic resection is hyaluronic acid, which comes in commercial preloaded 5 ml syringes containing the blue color. Hyaluronic acid remains longer in the submucosa because it is not absorbed quickly, keeping elevations raised for 45 minutes to an hour. However, it is not available everywhere in the world. You can prepare the solution yourself using normal saline. Normal saline is a cheaper, established alternative that has been used for submucosal injection for over 20 years with excellent results. Adding a blue contrast mixture to the saline helps distinguish the muscle layer from the submucosal aspects during tunneling procedures, POEM, or resections.