Background: Adenomyosis and leiomyoma are common benign uterine disorders with overlapping clinical and imaging features, making accurate preoperative diagnosis challenging. This study evaluated the diagnostic value of individual transvaginal ultrasonography (TVS) criteria for adenomyosis and leiomyoma using histopathology as the reference standard. Methods: This analytical cross-sectional study was conducted among 150 women aged 30–55 years with TVS-diagnosed adenomyosis, leiomyoma, or both who subsequently underwent hysterectomy, myomectomy, or adenomyomectomy and had histopathological confirmation. Participants were enrolled using purposive sampling. Individual TVS criteria for adenomyosis and leiomyoma were compared with corresponding histopathological findings. Statistical analyses were performed using SPSS version 26.0, with p<0.05 considered statistically significant. Results: Leiomyoma was the most common diagnosis (61.33%), followed by combined adenomyosis and leiomyoma (26.00%) and adenomyosis alone (12.67%). For adenomyosis, no distinction of the endometrial-myometrial junction (78.9%), asymmetry of the anterior and posterior myometrium (83.3%), heterogeneous myometrial echotexture (80.3%) and myometrial cysts with fibrosis (62.5%) showed significant associations with histopathology (all p<0.0001). For leiomyoma, clear tumor margin demarcation (96.7%), peripheral vascularity on color Doppler (95.6%), irregular uterine surface (93.5%) and irregular endometrial surface (95.7%) were also significantly associated with histopathological confirmation (p≤0.005). Conclusion: Individual TVS criteria demonstrated significant diagnostic value for adenomyosis and leiomyoma. Recognition of these sonographic features may improve preoperative diagnostic accuracy and support appropriate clinical management.