In recent years with the continuous improvement of ART technology, it has brought new hope to infertile couples, however more than half of the patients still experience multiple transfer failures. Abnormalities in the structure of the uterine cavity are one of the main factors that lead to the failure of embryo implantation. Hysteroscopic metroplasty with cold scissors is an innovative technique of our team, in which micro-scissors are used in the procedure instead of the previous electric knife. Our previous study found that this technique has the effect of improving fertility outcomes in patients with T-shaped uterus.

Based on the previous study, this study is an open randomized controlled trial to include patients with more than 2 or more ART implantation failures. For the first time, cold knife hysteroscopic hysterectomy was used to treat patients with cryptic uterine stenosis in patients with repeated RIF implantation failures to assess the clinical efficacy of the technique and to investigate the effect of this technique on the pregnancy outcome of reimplantation of embryos in patients with repeated ART implantation failures. Meanwhile, this project is the first to study the diagnostic value of transvaginal 3D ultrasound/MRI for the assessment of uterine cavity status in patients with RIF, with a view to exploring the value of noninvasive imaging as an alternative to invasive hysteroscopy in the clinical management of RIF. The aim of the study is to provide a reference for early diagnosis and treatment of patients with repeated ART implantation failures, and to improve the pregnancy outcome of their reimplanted embryos.

Inclusion Criteria:

• At least twice previous implantation failures
• Willing to receive further embryo transfer

Exclusion Criteria:

• Sturctural intrauterine lesions
• Severe adenomyosis
• Premature ovarian failure
• BMI > 35 kg/m^2
• Severe systemic disease or maligant tumor