Failure of a Single-Session Intralesional Triamcinolone Injection to Prevent a Stricture After ≥90% Circumferential Rectal Endoscopic Submucosal Dissection: A Case Report.

Near-circumferential colorectal endoscopic submucosal dissection (ESD) carries a substantial risk of postoperative strictures, with reported rates of 11-43% when mucosal defects involve ≥90% of the luminal circumference and up to 50-71% after total circumferential resection. A postoperative stricture sometimes requires repeated interventions, such as endoscopic balloon dilation, which can impose a significant burden on both patients and healthcare providers. Although an intralesional triamcinolone acetonide (TAC) injection is widely used to prevent strictures after esophageal ESD, its efficacy after colorectal ESD remains unclear. We describe a case of near-circumferential rectal ESD in which prophylactic intralesional TAC injection was administered, yet a postoperative rectal stricture still developed and required endoscopic balloon dilation. A 70 mm type 0-Is + IIa lesion (Paris classification) located in the upper rectum, involving more than 90% of the luminal circumference, was successfully resected en bloc by ESD. Prophylactic intralesional TAC (50 mg) was injected into the post-ESD ulcer base immediately after resection. The postoperative course was uneventful. The patient had no symptoms at the one-month postoperative follow-up visit. At that time, a follow-up colonoscopy was scheduled for approximately six weeks later. However, constipation developed approximately six weeks after ESD and was initially managed with laxatives prescribed by another physician at our hospital. As the constipation worsened, the patient revisited our department, and a colonoscopy was performed the following day, revealing a rectal stricture. Endoscopic balloon dilation was subsequently performed, resulting in symptomatic and endoscopic improvement. A rectal stricture can still develop after near-circumferential colorectal ESD despite prophylactic intralesional TAC injection. These findings highlight the limitations of a single-session intralesional TAC injection and underscore the need for optimized preventive strategies and careful postoperative surveillance in high-risk colorectal ESD involving more than 90% of the luminal circumference.