Background Adenomyosis and leiomyoma are prevalent benign uterine pathologies causing symptoms such as abnormal uterine bleeding and chronic pelvic pain. Distinguishing these conditions is critical for selecting suitable therapeutic strategies. Ultrasound, a widely accessible imaging technique, is frequently used for the diagnosis of these uterine abnormalities. This study aimed to evaluate the diagnostic accuracy of transvaginal ultrasound for detecting adenomyosis, leiomyoma, or both, compared to histopathological results. Methodology This cross-sectional study was conducted at Liaqat Memorial Hospital affiliated with KMU Institute of Medical Sciences Kohat, involving a total of 97 women who underwent a thorough clinical examination, followed by transvaginal 3D ultrasound and, where necessary, histopathological examination of surgical specimens . A control group of 30 women with no abnormal findings on clinical examination, transvaginal 3d ultrasound and histopathology was included to verify ultrasound specificity. The study group consisted of 67 patients diagnosed with suspected adenomyosis, leiomyoma, or combined pathology based on ultrasound findings. Transvaginal ultrasound examinations were conducted, followed by histopathological analysis of surgical specimens for confirmation. The study measured the sensitivity, specificity, positive predictive value, and negative predictive value of transvaginal 3D ultrasound findings, using histopathology as the reference standard. Results For diagnosing adenomyosis, transvaginal 3D ultrasound exhibited a sensitivity of 88.1% and a specificity of 75.0%. In cases of leiomyoma, ultrasound demonstrated a sensitivity of 92.5% and a specificity of 82.4%. When both adenomyosis and leiomyoma were present, the sensitivity was 84.3%, with a specificity of 72.1%. Out of 67 participants with suspected pathology, histopathological analysis confirmed 46 cases of leiomyoma, 21 cases of adenomyosis, and 10 cases with combined pathology. The control group results supported ultrasound’s high specificity in ruling out disease in patients with no abnormal findings. Conclusion Transvaginal 3D ultrasound is an effective diagnostic tool for detecting adenomyosis and leiomyoma, showing high sensitivity and specificity, especially when correlated with histopathological findings. Although ultrasound performs well in identifying these conditions, cases with combined pathology may benefit from supplementary imaging or follow-up to ensure diagnostic precision. Histopathological verification remains crucial for cases requiring surgical intervention.