A slightly dense shadow in the left adnexal region may indicate the presence of an adnexal mass. Generally speaking, the presence of a slightly dense shadow in the left adnexal region indicates that there may be an abnormal mass in the adnexal region (fallopian tube and ovary), and the most common ones include corpus luteum cyst, tubo-ovarian cyst, plasma cystadenoma of the ovary, and plasma cystadenocarcinoma of the ovary, etc. However, the diagnosis cannot be directly determined by imaging, as well as the type of pathology. However, since the benign or malignant nature of the mass and the type of pathology cannot be directly determined by imaging, further pathologic examination is needed to confirm the diagnosis. In case of luteal cyst, physiological changes such as luteal cysts do not require intervention and close observation is sufficient; in case of ovarian tumors, resection and subsequent radiotherapy are required according to the pathological results. To sum up, it is recommended to consult a doctor in time for standardized diagnosis and treatment.