Dynamic Submucosal Injection Technique

This article describes the submucosal injection technique applied in the endoscopic resection of non-polypoid colorectal neoplasms, with an emphasis on a particular technique, the dynamic submucosal injection technique.

Submucosal injection is an integral part of most endoscopic mucosal resection (EMR) techniques. Rosenberg in the United States first described the use of submucosal injection in 1955, using a rigid needle passed through a rigid sigmoidoscope for the purpose of decreasing through and through coagulation of the colonic wall. He was concerned that through-and-through coagulation might lead to injury of the surrounding organ, delayed bleeding, “when separation of too deep a slough uncovers a blood vessel of large size”; intestinal obstruction due to adhesion that formed over a coagulated area; and peritonitis, when the necrotic area is adjacent to the peritoneum.

Deyhle and colleagues in Germany applied the described principles of submucosal injection as a method for flexible endoscopic electroresection of sessile colonic polyp in 1973. After testing the concept in a canine model, they were the first to describe the safety of injecting saline through a flexible injection needle before endoscopic resection of 7 sessile colonic polyps. The submucosal injection technique has since become an integral part of endoscopic mucosal resection and submucosal dissection techniques. In addition, the submucosal injection technique has been applied in the treatment of gastrointestinal bleeding to inject sclerosant or diluted epinephrine to treat variceal and nonvariceal bleeding, respectively, and in marking using India ink or carbon particles.

The static submucosal injection technique

The technique used to inject the submucosa for endoscopic resection has changed little since the early descriptions. During standard submucosal injection (in this article, the authors propose the term static submucosal injection technique ), the needle, after being pushed into the submucosa, is kept stationary until an adequate volume of injection has been slowly infused. The lumen is kept fully insufflated to visualize the position of the needle. During resection of a large lesion, injection is recommended to begin at the site away from the endoscope. A common disappointment in performing the static submucosal injection technique is that the bulge is insufficient for capturing the lesion by the snare. In these cases, many endoscopists report that the injectant dissipates too fast ( Fig. 1 ) and then the snare cannot effectively capture the targeted lesion. Of the several different solutions that have been described to create a larger bulge, only Glyceol (a hypertonic solution consisting of 10% glycerol and 5% fructose in normal saline solution) and hyaluronate are commonly used in Japan.

The dynamic submucosal injection technique

The authors developed the dynamic submucosal injection technique to facilitate the formation of a massive bulge under the lesion using saline solution and a standard sclerotherapy needle to perform a safe and effective endoscopic mucosal resection and submucosal dissection. To begin, the catheter is engaged at the targeted site of injection, the needle is then exposed into the submucosal, and a small amount (0.5 to 1 mL) of saline is injected to confirm that the tip of the needle is in the submucosa. Subsequent injection is performed through the 25-gauge needle rapidly, but rather than being static, the needle is moved within the injection site by pulling the catheter back slowly or by slightly deflecting the tip of the endoscope. The lumen is suctioned—occasionally to the point of collapse—to increase the size of the bulge. The shape of the submucosal accumulation of the saline is, therefore, molded so that the submucosal bleb raises the flat lesion and then can be easily resected. In EMR cases, the lesion is then resected en-bloc or piecemeal using a commercially available stiff snare. The authors use the technique routinely in practice (representative images are shown in Figs. 2–6 ).