Endoscopic submucosal dissection (ESD) is a curative treatment of choice for superficial gastric precancerous lesions and early gastric cancer (EGC) [1], [2]. However, various complications, such as bleeding, perforation, aspiration pneumonia, pyloric stenosis, and transient bacteremia, can occur during or after gastric ESD [3]. Intra-procedural bleeding and post-ESD bleeding are some of the major surgery complications, so adequate classification and prevention are important. [4], [5]. Post-ESD bleeding occurs in abo approximately 2%–15% of cases [6]. Post-ESD bleeding can be classified into early delayed bleeding (within 24 h after ESD) and late delayed bleeding (more than 24 h after ESD) [7], [8]. To decrease the incidence of late delayed post-ESD bleeding, scheduled second-look endoscopy is sometimes performed on the day following ESD [9].

However, there have not been any studies on the efficacy of second-look endoscopy for the prevention of early delayed post-ESD bleeding. One of the factors associated with post-ESD bleeding is a long procedure time [10], [11]. Prolonged ESD time may burden the operator; if a significant amount of time is required to perform the submucosal dissection, the operator may become exhausted and have difficulty concentrating while performing hemostasis. Also, repeatedly injected submucosal solutions during a prolonged ESD can remain in the ESD ulcer base, making fragile vessels invisible. We hypothesized that hidden fragile vessels would be a high-risk factor for early delayed post-ESD bleeding and exposed as the submucosal injection is absorbed over time. Also, a brief break would allow the operator to better focus on the ESD ulcer site.

According to these hypotheses, an immediate second-look endoscopy to reconfirm the ESD ulcer site could be beneficial. This study aimed to determine if immediate second-look endoscopy can reduce the risk of post-ESD bleeding, especially early delayed post-ESD bleeding.