The causes of formation of adnexal cysts, whether left or right, are broadly classified as physiological cysts (functional cysts), inflammatory cysts, endometriotic cysts (chocolate cysts) and neoplastic cysts (pathological cysts) Normally, the dominant follicle on one ovary contains a mature egg, which disappears after the egg has been released. When the follicle on the ovary is unable to release the egg, it fills with fluid and swells, forming a follicular cyst; when the remaining follicle does not dissolve and continues to fill with fluid and swell, a luteal cyst is formed. Clinically, the risk factors and people at high risk for functional ovarian cysts are: previous history of ovarian cysts, currently taking clomiphene to promote ovulation, and using low-dose progestin-based contraceptives. Ovarian chocolate cysts, medically known as ovarian endometriotic cysts, are endometrium-like tissues planted in the ovaries that undergo cyclic proliferation and shedding with menstruation, and the accumulation of menstrual blood swells to form cysts. The cyst is named after the dark red, old menstrual blood that flows out after rupture, resembling hot chocolate. It should be noted that for those who wish to have children, pregnancy should be induced as early as possible. Once pregnancy occurs, the ectopic endometrial lesion will necrotropically atrophy and the symptoms will be relieved and hopefully cured after delivery. Inflammatory cysts are most commonly tubo-ovarian cysts, which are caused by inflammation of the fallopian tubes resulting in adhesions at their ends and inability to remove fluid from the middle, forming a salami-like swelling. Tubo-ovarian cysts are also often formed by inflammatory adhesions wrapped in inflammatory exudate. The cause of pathological cyst formation is unclear and has some relationship with genetics, but most of them cannot be found.