Terminal Ileal Ulcers: Endoscopic Predictors for the Later Development of Crohn's Disease

Background: Terminal ileal ulcers (TIUs) are frequently identified during colonoscopy but are often attributed to nonspecific etiologies, potentially delaying the diagnosis of Crohn's disease (CD). This study aimed to evaluate the utility of TIU as an early diagnostic marker and to determine whether diagnosis at the isolated TIU stage impacts long-term surgical outcomes. Methods: In this single-center, retrospective cohort study, consecutive adult patients with TIU detected via colonoscopy over a 10-year period were analyzed. Patients were stratified into CD-TIU and non-CD-TIU cohorts based on longitudinal follow-up. Clinical, endoscopic, and laboratory parameters were compared. Long-term surgical outcomes of patients diagnosed at the isolated TIU stage (Montreal classification L1) were compared with those of patients with established ileocolonic disease (Montreal classification L3). Results: Of the 66 patients included in the final analysis, 18 (27.3%) were ultimately diagnosed with CD. Specific endoscopic features-including longitudinal or fissuring ulcers (50.0% vs. 6.3%, p < 0.001), ileocecal valve deformity (50.0% vs. 18.8%, p = 0.011), and increased ulcer dimensions (9.11 mm vs. 4.60 mm, p = 0.002)-were significantly associated with a CD diagnosis. Notably, patients diagnosed at the TIU stage (CD-L1) exhibited a significantly lower surgical rate compared to those with established ileocolonic disease (CD-L3) (5.6% vs. 70.2%, p < 0.001). Conclusions: TIU, particularly when characterized by longitudinal morphology or ileocecal valve involvement, constitutes a critical early manifestation of CD. Diagnosis at the isolated TIU stage is associated with a lower long-term surgical risk compared to established ileocolonic disease, likely reflecting the influence of disease phenotype. These findings underscore the imperative for meticulous endoscopic evaluation to identify early-stage disease.