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.

Inclusion Criteria:

• Patients who were admitted to Shenzhen Hospital of Southern Medical University from 2015 to 2023 and underwent colorectal endoscopic ultrasound.
• Patients diagnosed with colorectal submucosal tumors (subepithelial lesions) according to the Chinese expert consensus on the endoscopic diagnosis and treatment of gastrointestinal submucosal tumors (2023 edition).

Exclusion Criteria:

• Patients with endoscopic ultrasound diagnosis of non-submucosal tumors.

This study includes patients who were admitted to Shenzhen Hospital of Southern Medical University between 2015 and 2023 and underwent colorectal endoscopic ultrasound (EUS). Eligible participants are those diagnosed with colorectal submucosal tumors/subepithelial lesions based on the Chinese expert consensus on endoscopic diagnosis and treatment of gastrointestinal submucosal tumors (2023 edition) and related criteria. Patients whose EUS findings did not support a diagnosis of a submucosal tumor/subepithelial lesion were excluded.