Left adnexal cysts are a series of cysts that occur in the fallopian tubes and ovaries, including tubal tract cysts, tubo-ovarian cysts, and ovarian cysts, in addition to inflammatory masses and hydrocele in the fallopian tubes. Tubal tract cysts tend to be small and are usually found during other pelvic and abdominal surgeries and can be surgically removed together. The latter two are also not uncommon clinically and are mostly inflammatory effusions, often with a history of pelvic inflammatory disease. Ovarian cysts are the most common type of adnexal cysts in clinical practice and include functional ovarian cysts such as follicular cysts and luteal cysts, which often occur in women of childbearing age. They are followed by pathological cysts such as epithelial cysts and teratomas. In addition, ovarian chocolate cysts due to endometriosis (EMT) are not uncommon. Adnexal cysts are treated differently depending on their origin: 1. Physiological cysts (functional cysts), which tend to disappear on their own, can gradually shrink with menstrual flow and can be reviewed regularly by ultrasound without treatment, unless they are accompanied by severe bleeding or torsion before surgery is required. 2. Pathological cysts, on the other hand, must be surgically removed and attention should be paid to their postoperative pathological type, whether benign or malignant. Surgery can be divided into adnexal resection (in postmenopausal women) and mass debridement, which should be performed in young women to preserve as much of the remaining ovarian tissue as possible. Currently, unless particularly large cysts and tumors considered malignant or junctional, ovarian masses can usually be removed by minimally invasive laparoscopic surgery. 3. For chocolate cysts (endometriotic cysts), surgery is recommended because such cysts can lead to infertility and also have a considerable chance of malignancy, and should be actively treated despite being prone to recurrence. For inflammatory cysts such as tubal inflammation or encapsulated effusion, conservative anti-inflammatory treatment is the mainstay. If the anti-inflammatory effect is unsatisfactory and there are repeated acute attacks, then surgical treatment is also available.