This study aims to evaluate the diagnostic accuracy of endoscopic ultrasound (EUS) for colorectal submucosal tumors/lesions (SMTs/SELs) and to identify factors associated with correct EUS diagnosis. Using cases with histopathologic confirmation as the reference standard, EUS-based preoperative diagnoses will be compared with final pathology to estimate overall accuracy and accuracy across different lesion types. Potential influencing factors-including lesion location, size, echogenicity, layer of origin, image quality, operator experience and training, and EUS equipment/probe type-will be analyzed to determine independent predictors of diagnostic concordance. The findings are expected to inform optimization of EUS examination and interpretation for colorectal submucosal lesions, thereby improving clinical decision-making and overall quality of care.