Introduction: In gynecology and ultrasonography, adnexal masses are a major health concern. Ultrasonography and International Ovarian Tumor Analysis (IOTA) criteria are crucial for diagnosing and identifying malignant grades, and an accurate distinction by non-invasive techniques is necessary for proper care. Methods: From January to May 2025, 400 patients who presented with adnexal masses at the Saudi Hospital for Obstetrics and Gynecology in Khartoum, Sudan, participated in a descriptive cross-sectional study. Adnexal lesions were assessed using transvaginal and abdominal ultrasonography, with the IOTA Simple Rules (SR) employed for classification. To evaluate associations with ultrasound results and final diagnoses, information on patient demographics, age, symptoms, and medical history was examined. Result: The age categories of 26–40 and 41–55 were the most impacted. The majority of patients experienced symptoms, with pain accounting for about 43.3% of cases. According to the IOTA SR criteria, ultrasonography identified 22% of masses as malignant and 68.8% as benign. Ultrasound characteristics, such as uneven shape, ascites, papillary projections, and vascularity, were found to be significantly associated with malignancy. Malignant lesions were also significantly associated with older age and a history of breast cancer. According to statistical analyses, ovarian cancer can be accurately predicted by certain ultrasonographic features using IOTA Simple Rules. In conclusion, ultrasonography is a reliable and efficient method for assessing and categorizing adnexal masses when used following IOTA guidelines. Combining the patient's age, medical history, and ultrasound characteristics improves diagnostic precision, enables prompt and effective treatment, and lowers the risk of surgery.