Injection therapy in the field of gastroenterology is the directed delivery of a liquid agent into the wall of the gastrointestinal (GI) tract or adjacent structures.¹ This is utilized for a variety of indications including, but not limited to, the following: to treat GI bleeding from lesions in the upper and lower GI tract; to deliver medications such as botulinum toxin to the lower esophageal sphincter to treat achalasia, corticosteroids for esophageal strictures; to inject tattooing agents such as India ink submucosally to mark an area; and to inject saline submucosally to lift a lesion prior to endoscopic removal.¹ This chapter will focus on applications of injection therapy for nonvariceal bleeding.

Endoscopic injection is used for the treatment of actively bleeding lesions and to prevent rebleeding from lesions with high-risk stigmata. Dilute epinephrine is most commonly used and works through a combination of tamponade by volume effect, vasoconstriction, and direct effect on clotting cascade.² Epinephrine injection is highly effective for achieving hemostasis and has been found to decrease the rebleeding rate, need for surgery, and mortality rate for peptic ulcer bleeding.³ Epinephrine injection with a second modality such as clipping or cautery further reduces these risks compared to epinephrine injection alone⁴ and is thus recommended for definitive therapy.⁵,⁶,⁷,⁸ Other injection agents such as sclerosants and glues work through direct tissue effect; however, they are less well studied and associated with higher adverse events rates compared to epinephrine.⁹ Details of the injection procedure are described below.