Cesarean scar pregnancy (CSP) is a special type of ectopic pregnancy with an incidence of about 1:1800 to 1:2216, accounting for 6.1% of ectopic pregnancies. Due to its anatomical location and pathophysiological peculiarities, there is no ideal and unified treatment standard for this disease, and improper clinical management may result in uncontrollable hemorrhage or prolonged disease, often leading to hysterectomy. In recent years, we have successfully preserved the uterus by laparoscopically blocking the uterine arteries bilaterally and then performing hysterectomy in CSP with failed initial treatment, and achieved satisfactory treatment results. The four cases of CSP who were transferred to our hospital between May 2006 and May 2009 due to failure of external treatment and underwent conservative laparoscopic surgery are reported as follows. I. Clinical data 1. General information: The patients’ ages ranged from 28 to 36 years, with an average of 31.8 years. 3 patients had a history of 1 previous cesarean delivery and 1 patient had a history of 2 cesarean deliveries, and the interval between the onset and the last cesarean delivery ranged from 1.8 to 4.5 years, with an average of 3.1 years. 2. Clinical symptoms and initial treatment: case 1 had vaginal bleeding on 52 days of menopause, positive urine HCG, ultrasound indicating intrauterine pregnancy, misdiagnosed as pre-eclampsia and scraping, and was transferred to our hospital in an emergency with massive vaginal bleeding during the operation; case 2 had menopause on 40 days, positive urine HCG, misdiagnosed as early intrauterine pregnancy and had a medication abortion, and was cleared because there was no tissue discharge, and the cleared material was pathologically visible as villi, and had vaginal bleeding for 3 weeks after the operation. There was vaginal bleeding for 3 weeks after the operation, blood human chorionic gonadotropin (HCG) was 265.8 IU/L, ultrasound showed heterogeneous echogenicity of 3.1×3.5 cm in the lower uterine segment, convex to the plasma layer of the uterus, rich local blood supply, diagnosed as CSP, oral mifepristone treatment for two weeks, blood HCG decreased to 81.2 IU/L. Case 3 was treated with mifepristone for two weeks, blood HCG decreased to 81.2 IU/L, intermittent frequent vaginal bleeding more than usual menstrual volume, ultrasound indicated a 5.6×4.5 cm heterogeneous mass in the lower uterine segment, rich blood supply, blood flow index 0.23; Case 3 was treated with mifepristone for 42 days, blood HCG 11286 IU/L, external ultrasound indicated CSP and scraping, vaginal bleeding still occurred 2 weeks after the operation, blood HCG 8756 IU/L, MTX 60mg was given. After 5 days of intramuscular injection, she was given mifepristone 50mg orally for 3 days, blood HCG was 1075 IU/L, and the extent of scar pregnancy increased to 7.2×5.3cm. After 48 days of menopause, the blood HCG was 10504 IU/L, the diameter of the lower uterine mass was 4.5 cm, and the local blood supply was rich, the diagnosis was CSP, and there was excessive vaginal bleeding after 3 times of MTX intramuscular injection. 3. Treatment: All four patients underwent laparoscopic uterine artery block and uterine scar pregnancy lesion excision. Case 1 was admitted to the hospital in an emergency and ultrasound examination showed solid inhomogeneous hypoechoicity of about 4 cm at the incision of the myocardial dissection of the lower anterior wall, which was diagnosed as CSP, and a uterine balloon was placed in the lower uterine segment under ultrasound guidance and 20 ml of saline was injected to reduce vaginal bleeding by temporary compression before laparoscopic surgery. Laparoscopically, all four pregnancy lesions were seen to protrude into the plasma layer of the uterus, with angry vascularization on the surface of the lesions. In cases 2 and 3, the masses were larger and extended into the broad ligament on both sides. The uterine arteries were isolated by opening the posterior lobe of the broad ligament 2 cm above the uterosacral ligament and ligated with a No. 1 dexon wire to block the uterine artery blood supply. After bilateral uterine artery blockade, active vaginal bleeding was stopped by withdrawing the case 1 uterine pressure balloon. After uterine artery blockade followed by focal resection, the bladder was opened uterine reflexion subperitoneal pushing of the bladder followed by laparoscopically supervised aspiration to aspirate most of the pregnancy tissue until the mass was significantly reduced and then focal resection was performed. Intraoperatively, the myometrial tissue at the implantation site was seen to be thin, and there was a clear demarcation between it and the normal myometrial tissue. After excision of the lesion, the myometrial layer was successively sutured with MTX 50mg multi-point injection at the uterine incision. 4. Results: All surgeries were completed successfully at one time, without intermediate open abdomen and without surgical complications. The surgical time was 60-80 minutes, with an average of 68.2 minutes; the blood loss was 30-70 ml, with an average of 50 ml; the patients all recovered well after surgery, and the pathology of villi was visible in the resected myometrial scar tissue, and the blood HCG decreased to normal 3 weeks after surgery, and the menstruation resumed in 23-35 days. In the postoperative follow-up period of 3~35 months, menstruation was regular, and all patients were contraceptive after surgery, and no pregnancy occurred yet. Second, discussion 1. Analysis of the reasons for the failure of treatment of cesarean scar pregnancy: CSP has a special pathophysiological basis. Firstly, the gestational sac in CSP is not in the uterine cavity and the chorionic villi are planted in the lower part of the uterus at the cesarean scar and then grow further into the uterine cavity or towards the plasma layer of the uterus; secondly, there is a defect in the myometrium at the cesarean scar and usually a weak or absent myometrium between the bladder and the gestational sac is visible on ultrasound and part of the gestational sac protrudes towards the plasma surface of the uterus. Due to the marked defect in the myometrial tissue at the embryo implantation site, the metaplastic vasculature formation is impaired, resulting in abnormal vascular proliferation. Based on these pathophysiological bases, curettage should not usually be used as the initial treatment option for CSP, and both cases treated with curettage in this paper failed. The main reasons are: scraping not only makes it difficult to completely remove the gestational trophoblast tissue inside the scar, but also allows the residual villi to continue to grow and lead to treatment failure; furthermore, the weak myometrium at the bed site is prone to uterine perforation and even bladder damage; furthermore, the weak myometrium at the uterine scar lacks an effective uterine contraction mechanism to stop bleeding, and it has been reported in the literature that uncontrollable hemorrhage can occur during scraping in about 76.1% of patients. The literature reports that uncontrollable hemorrhage can occur in about 76.1% of patients during curettage. The success rate of pharmacological treatment for CSP has been reported in the literature to be variable. The formation of scarred fibrous tissue at the site of pregnancy makes the drug permeability poor, and the pregnancy material cannot be discharged in a timely manner, resulting in prolonged disease and increased chances of pelvic infection, and the possibility of recurrent massive bleeding due to local tissue necrosis during treatment. In recent years, uterine artery embolization (UAE) has been gradually applied in the treatment of CSP. UAE can significantly reduce the blood supply to the lesion to achieve rapid hemostasis, while local ischemia and hypoxia in the scar lesion promote embryonic and trophoblast necrosis and atrophy. Since the residual villi tissue can continue to grow with the formation of lateral branch circulation after embolization, UAE alone should be carefully selected as a treatment for CSP, especially in the case of large pregnancy lesions where local tissue necrosis is difficult to absorb. In this paper, one case failed to be treated with UAE, and such cases should be treated with other conservative treatment methods after UAE. 2. Advantages of laparoscopic uterine artery block and lesion excision: The most common reasons for the failure of initial treatment of CSP are acute hemorrhage or incomplete removal of pregnancy tissue leading to prolonged disease. Therefore, timely and effective hemostasis and complete removal of the lesion are essential to ensure successful re-treatment. In patients with long duration of the disease, the pregnancy mass is usually large, and the complete removal of the lesion is an issue that requires careful clinical consideration. In the past, hysterectomy was often chosen for cases with failed primary treatment, but hysterectomy brings great psychological pressure and trauma to young women, especially for those who still have fertility requirements. Based on the pathophysiological mechanism of CSP, most scholars believe that excision of the scarred pregnancy lesion with incisional suturing and preservation of the uterus is the best treatment for CSP at present. Not only can resection of the lesion avoid residual pregnancy tissue, but also the blood β-hCG can be normalized rapidly after surgery; moreover, the scar tissue at the chorionic villus implantation site has obvious defects, and complete resection can effectively remove the tiny cavity at the scar site, effectively avoiding the recurrence of CSP and facilitating the restoration of normal pregnancy. Because of the rich blood supply at the lesion site, large amount of bleeding is likely to occur during resection, and open surgery can quickly suture to stop the bleeding, so resection of CSP lesions is mostly done through the open route. With the application of UAE, the blood supply to the lesion site can be significantly reduced, providing a safe and effective guarantee for laparoscopic surgery, and laparoscopic lesion excision and uterine repair have the advantages of less operating time, shorter hospital stay, and faster patient recovery. However, it is difficult to promote the use of UAE in clinical practice because of the high requirements of not only equipment and operation techniques, but also the fact that it cannot be done at the same time as laparoscopic surgery and the high medical costs. In recent years, we have adopted laparoscopic bilateral uterine artery blockage to reduce the blood supply to the lesion, followed by scar pregnancy lesion excision and uterine repair. This surgical approach not only ensures the safety and effectiveness of the procedure, but also allows both surgical operations to be performed laparoscopically, significantly reducing medical expenses and conforming to the principles of health economics. It is worth mentioning that when the bilateral uterine artery block is completed, the bladder is opened to reflex subperitoneal pushing of the bladder, and then the uterus is aspirated under laparoscopic supervision, and then the lesion is removed after the volume of the pregnancy mass is significantly reduced, and the scarred myometrial tissue of the uterus at the embryo implantation can be clearly identified after aspiration, and there is a clear demarcation between the normal myometrial tissue. This approach can effectively reduce the difficulty of lesion removal, reduce the complications and shorten the overall operation time, which highlights the advantages of laparoscopic surgery. In this paper, all four cases were successfully completed with an average intraoperative blood loss of only 50 ml and rapid postoperative recovery. In conclusion, with the maturation of laparoscopic technology and the deepening of the understanding of CSP, laparoscopic uterine artery block and focal resection have the advantages of being minimally invasive, effective and economical, and will become an effective method for the treatment of primary failed CSP cases.