Ovarian cysts are a frequent and common disease in gynecology. If conservative treatment is not effective, surgical treatment is required. In terms of surgical treatment, it includes traditional gynecological surgery and various types of minimally invasive surgery. With the development of imaging interventional technology and the continuous improvement of machine equipment and treatment methods, minimally invasive interventional treatment of ovarian cysts is becoming more and more clinically recognized and popular among patients. However, in the current minimally invasive treatment of ovarian cysts, CT-guided and B-ultrasound-guided are all anterior approach puncture treatment, which has a problem: a significant part of ovarian cysts are located in the posterior part of the uterus, close to the posterior pelvic wall, so the path of puncture through the anterior wall is long and the number of organs passed through is bound to cause great damage, plus the puncture point cannot reach the lowest point of the cyst when the cyst is more downward due to the influence of the pubic symphysis, which affects the treatment effect. Although the CT-guided (B-ultrasound) anterior approach interventional sclerotherapy for ovarian cysts has its certain shortcomings, there has been a great progress in the treatment of ovarian cysts compared with traditional surgery. We now present a review of its treatment methods and therapeutic effects, and the choice of the puncture route in the light of the literature. 1. Development of CT-guided (ultrasound) interventional sclerotherapy for ovarian cysts 1.1 CT-guided (ultrasound) interventional sclerotherapy for ovarian cysts was first applied in clinical practice in the early 1990s, mainly for simple cysts and chocolate cysts of the ovary. In terms of treatment age, the domestic literature reports that the maximum treatment age is 82 years old and the minimum treatment age is 13 years old. At present, CT-guided (ultrasound) interventional sclerotherapy for ovarian cysts has become a routine clinical treatment method. It has a high application value in the treatment of benign gynecologic cysts. 1.2 With this technique, a clear diagnosis before surgery is an important prerequisite for successful treatment, often after CT and B-ultrasound. The site, size, density and thickness of the cyst wall are observed to determine the nature of the cyst, select the indications, determine the puncture route, and choose the puncture equipment and method. Nuclear magnetic examination can be performed in difficult cases. 1.3 After successful puncture, how to ensure that the cystic fluid is extracted at one time and the sclerosing agent is injected without extravasation is the key to successful sclerotherapy. The choice of puncture point and puncture method is important. The specific operation method is to select the best skin entry point and entry angle under CT positioning, apply local anesthesia with 2% lidocaine, and puncture the cyst (as far as possible at the lowest point of the cyst) with a 16-18G puncture needle under the guidance of CT images. The cyst fluid was aspirated as much as possible and routinely sent for pathological examination of exfoliated cells. The cyst was flushed with saline according to the amount of cyst fluid aspirated, and further confirmed that the puncture needle was located within the cyst when 5-10 ml of 1% lidocaine was injected for intracavitary anesthesia. After anesthesia, anhydrous ethanol was injected for sclerosis. The amount of anhydrous ethanol injected depends on the amount of extracted fluid, generally 40% to 60% of the extracted cystic fluid, and the total amount should not exceed 200 ml. repeatedly flush with body rotation for complete sclerosis, and finally leave 5 to 10 ml of anhydrous ethanol. 1.4 After CT-guided anhydrous ethanol sclerosis, ovarian cysts are treated by impotence of cysts after minimally invasive intervention. The cysts shrank to varying degrees in 100% of cases, and the cure rate could reach more than 90%. The recurrence rate was 5.2% at the one-year post-treatment review, and the reasons for recurrence were related to the fact that anhydrous ethanol was not chosen as the sclerosing agent and the cysts were multi-roomed and not completely sclerosed. After this treatment the original abdominal pain and abdominal soreness symptoms basically disappeared. Complications were mainly pain, small amount of bleeding and puncture side injury. The incidence of complications was reported in the domestic literature as 8.9% to 19.6%. Some scholars have also adopted transvaginal puncture to reduce the complication rate to 4.3%. The rate of complications is related to the puncture route and also to the location of the cyst. Posterior ovarian cysts with a long transabdominal puncture route can cause more complications. 2.Treatment principle of CT-guided (ultrasound) interventional sclerotherapy for ovarian cysts 2.1 CT images are clear and can clearly show the location, size and proximity of ovarian cysts. Therefore, accurate puncture into the cyst cavity is possible under CT guidance. The needle entry point, the angle and depth of the needle entry are monitored in a timely manner. The accuracy of puncture is ensured. Thorough extraction of cyst fluid and introduction of sclerosing agent are ensured. And unnecessary side injuries were avoided as much as possible. 2.2 In the choice of sclerosing agent, anhydrous ethanol was preferred. This is because anhydrous ethanol has the ability to destroy the cyst wall cells to make them denatured, necrotic loss of secretion function and make the cyst can not recur, it can make the cyst cavity adhesion closure, it is inexpensive, easy to obtain, the efficacy is sure. Because of its irritation, individuals who are allergic to alcohol can choose other sclerosing agents, such as cod liver oil acid na, acetic acid, etc. However, its sclerosing effect is not as good as that of anhydrous ethanol. Generally patients can still tolerate the painful reaction brought about by anhydrous ethanol sclerosis by intracapsular anesthesia. The choice of ovarian cyst treatment There are many ways to treat ovarian cysts, all of which have their own advantages in terms of treatment effect and degree of damage. In traditional gynecological surgery, the patient’s ovaries are removed or the cyst is peeled off to preserve some ovarian tissue. This results in greater trauma to the patient, longer recovery time and more cost. Now it is not the preferred way; ultrasound and CT guided interventional sclerotherapy, navigation micro-electrode non-invasive therapy, etc. belong to minimally invasive surgery. However, for ovarian cysts with posterior uterus, ultrasound needs to be performed through the bladder and uterus and other organs causing certain side injuries, and the gas in the intestinal canal interferes with the ultrasound echo and affects the clarity of the image, making it difficult for ultrasound guidance to reach the lesion directly. CT-guided posterior approach for ovarian cysts can make up for the shortcomings of the technique. 4.The feasibility and superiority of CT-guided posterior approach for sclerosing ovarian cysts The posterior approach is to enter the pelvis through the skin, gluteus maximus muscle and pear-shaped muscle by puncture needle from the lower 1/4 quadrant of the gluteal sulcus, which is called the posterior approach. From the outer edge of the sacrococcygeal bone as the medial border, the internal iliac vessels and sciatic nerve as the lateral border, down to the triangular-like area of the pelvic floor, we call it the safety triangle. After a systematic local anatomical study, we found that this triangle avoids large blood vessels and nerves and is a safe needle entry area. It is a safe area for needle insertion to avoid damage to pelvic organs, blood vessels and nerves. The safety triangle is located in the lower 1/4 quadrant of the buttock and within the body projection of the sciatic nerve, and the anatomical adjacency of the pelvic tissues and organs can be clearly shown under CT. The CT-guided needle is inserted into the cyst, the cyst fluid is extracted, the sclerosing agent is injected with anhydrous ethanol, and a small amount of sclerosing agent is left in the cyst cavity after repeated flushing several times; the cyst atrophies to achieve the purpose of radical treatment of the cyst. CT-guided posterior approach interventional sclerotherapy for posterior ovarian cysts utilizes the advantages of CT high definition and high resolution; the posterior approach avoids the bladder, uterus, blood vessels and nerves. The posterior approach avoids the bladder, uterus, blood vessels and nerves. It makes up for the shortcomings of ultrasound intervention and other treatment methods. This technique can be completed by one person, with the advantages of simple method, safety and reliability, slight trauma, not affecting the function of ovaries, repeatable treatment, etc. The treatment effect is good. It is truly a minimally invasive treatment. CT-guided posterior approach interventional treatment for ovarian cysts has direct access, short route, does not involve the parenchymal organs, selective needle entry point and angle, the needle tip can reach the lowest point of the cyst, and the treatment is complete. CT-guided treatment of posterior ovarian cysts is a minimally invasive procedure that is incomparable to other treatment methods. This method has been successful in the treatment of posterior ovarian cysts in the uterus after exhaustive anatomical studies, with the guidance of CT high definition images and the convenient route of the posterior approach. We propose a new method of minimally invasive interventional sclerotherapy for posterior ovarian cysts with no pelvic organ collateral damage, complete treatment, low cost and short treatment course. The aim of minimally invasive and effective treatment was achieved. This access method is not only applicable to CT-guided diagnosis and treatment of ovarian cysts, but will also be adapted to the diagnosis and treatment of other pelvic lesions (e.g., periportal hyperplasia, tumors, uterine ovarian tumors, biopsy treatment of other pelvic tumors, pelvic lymph node biopsy, etc.). It has high innovation and practicality, and its market prospect is considerable, with good social and economic benefits. It has the value of promotion and popularization.