Hypoechoicity in the adnexal region is a result of ultrasound examination, which may be caused by normal follicles, tubal effusion, ovarian cysts, etc. 1. Normal follicles: follicles are normal germ cells of the ovary, and the ovary releases one follicle in each menstrual cycle. Ultrasound when the follicle is mature can show hypoechoicity in the adnexal area. 2. Tubal effusion: when there is effusion in the fallopian tube, hyperechoic adnexal area will also appear by ultrasound. 3. Ovarian cysts: Ovarian cysts may be physiologic, such as corpus luteum cysts, ultrasound will show hypoechoic adnexal area, which will disappear after menstruation. They may also be pathologic, for example, some benign ovarian tumors can be seen as hypoechoic areas on ultrasound. Therefore, ultrasound examination of hypoechoic adnexal area should be promptly consulted for early treatment.