Recently, the obstetrics team of the First Hospital of Chongqing Medical University successfully performed fetoscopy + placental anastomosis vascular laser electrocoagulation for a patient with twin fetal transfusion sign. In October 2012, Hu, who lives in Bishan County, Chongqing, was confirmed to have a twin pregnancy at about 50 days of menopause, and the family was in excitement and expectation. However, after receiving several ultrasound examinations in the local area, a strange phenomenon was discovered: the two fetuses, which had developed identically in the early stage, appeared to be one baby larger and one baby smaller at 24 weeks. The family was anxious and hastily transferred to the obstetrics department of the First Hospital of Chongqing Medical University, a prenatal diagnosis center in Chongqing, for examination. After examination, it was found that the weight of the small double was only about 2/3 of the large double. Not only that, but there was almost no more amniotic fluid around the small double, while there was a large amount of amniotic fluid around the large double. It turned out that Xiao Hu was suffering from an idiopathic disease in a single chorionic villous double amniotic sac twin pregnancy: twin fetus transfusion syndrome. The twin transfusion syndrome is a serious complication of single chorionic amniotic sac twin pregnancy with an incidence of 10% to 20%, and was first identified and proposed by Herhitz in 1941. Because of the anastomosis of the placental vessels, the blood donor develops anemia, dehydration, low amniotic fluid, and even death due to nutritional deficiency; the blood recipient develops increased blood volume, which can lead to serious complications such as congestive heart failure and fetal edema. Severe twin-fetus transfusion syndrome can result in intrauterine fetal death in one or both fetuses, with a perinatal mortality rate of up to 80%, and even if they survive, their neurological and cardiovascular complications are significantly higher. The patient not only showed the typical manifestations of twin-fetus transfusion syndrome such as excessive-hypohydramnios sequence and large weight difference, but also the umbilical artery flow spectrum of the younger twin showed a loss of the diastolic blood flow signal in the umbilical artery, which is a sign of frequent fetal death, and without active management, the younger twin would die within a short period of time due to death, and after the death of the younger twin, the older twin would also die within the next few weeks. The patient’s condition was urgent and the pregnant woman and her family were received by the head of obstetrics, Prof. Chia Hongbo, and Dr. Shuai Huang, who was in charge of intrauterine treatment of the fetus. After communication, the pregnant woman’s paternal grandparents even had a family history of large weight difference after the birth of twins and sudden death of one fetus, all of which implied a great risk of intrauterine death of the twins. After communication, the pregnant woman and her family requested an urgent surgical intervention: fetoscopic placental anastomosis with vascular electrocoagulation. The procedure was performed under local anesthesia because the pregnant woman was extremely concerned about the effect of drugs on the embryo. Through the successful guidance of ultrasound, the 3mm catheter successfully entered the amniotic cavity, and after placing the fetoscope, the baby’s limbs and hairs could be seen, and along the placental vessels, more anastomosing vessels could be seen around the amniotic septum, which are the “culprits” of the current physical condition of the big and small pairs. With the full cooperation of the operating room doctors, the obstetrician team successfully blocked the anastomotic vessels and the post-operative ultrasound showed that both fetuses were in good condition. The operation lasted about 50 minutes, with minimal bleeding of about 1 ml, and the patient was able to eat after the operation. Ultrasound follow-up on the first day after surgery revealed that there was recovery of umbilical cord blood flow in Shuang and he was discharged on the third postoperative day. The patient will receive bi-weekly follow-up for the rest of the year. Dr. Shuai Huang points out that the use of fetoscopy dates back to the 1970s. Fetoscopy can be used not only for the treatment of twin fetal transfusion syndrome, but also for fetoscopic umbilical vessel puncture for blood transfusion, fetoscopic amniotic septal stoma, fetoscopic biopsy (commonly used for fetal sampling and diagnosis of albinism), and examination of complex fetal appearance anomalies that cannot be identified by ultrasound. Through fetoscopy, it is not only possible to diagnose some congenital diseases, but also to intervene in utero for some diseases that seriously affect the prognosis of newborns at birth, advancing the time window for treatment of human diseases to the fetal period, which has a wide application prospect. Professor Qi Hongbo, director of obstetrics, pointed out that with the development of assisted reproduction technology and ovulation promotion technology, the incidence of twin pregnancies is increasing year by year, and the incidence of twin fetal transfusion syndrome is also increasing year by year, previously, for such patients, we could only give observation and follow-up, or travel to Beijing, Shanghai, Hong Kong and other places to perform fetoscopic surgery. As a prenatal diagnosis center in Chongqing, the Department of Obstetrics and Gynecology of the First Affiliated Hospital of Chongqing Medical Center has been striving to build a regional center of fetal medicine in the hope of benefiting mothers in the region. This surgery is the first fetoscopic surgery in our hospital, and it is also the most difficult anterior placenta surgery in fetoscopic surgery, the success of this surgery will greatly improve the level of fetal medicine in our department, and the standard of fetal medicine in the obstetrics department of the First Affiliated Hospital of Chongqing Medical University has entered the leading position in China. Surgical operation, fetoscopy work has been performed before, next, we will explore fetal surgery in conjunction with neonatal surgery of Chongqing Medical University to carry out surgical interventions such as fetal sacrococcygeal teratoma, congenital cystic adenoma of the lung, urethral valve disease, hydrocephalus, pleural effusion in the fetal period.