Abstract: Objective  To explore the impact of the thickness and morphology of the junctional zone(JZ) on the frozen embryo transfer(FET) in patients with adenomyosis. 
Methods  A retrospective analysis was performd on the clinical data of 85 patients with adenomyosis who underwent FET in the Department of Reproductive Medicine, the Fourth Hospital of Hebei Medical University. Long-acting gonadotrophin releasing hormone agonist(GnRH-a) down-regulation was used before the endometrium preparation. According to presence of pregnancy, they were divided into pregnancy group(n=45) and non-pregnancy group(n=40). The relationship between the thickness and morphology of the uterine JZ and clinical outcome under three-dimensional vaginal ultrasound was analyzed. 
Results  There were no significant differences between the two groups of patients in terms of age, years of infertility, body mass index, proportion of primary infertility, number of embryos transferred and thickness of endometrium(P＞0.05). There were no significant differences between the two groups of patients in thickness of uterine JZ during menstrual period, and after using GnRH-a once and twice(P＞0.05), however, there was a significant difference in the normal rate of JZ morphology between the two groups(P＜0.05). Multivariate logistic regression analysis related to the occurrence of pregnancy showed that JZ morphology after using GnRH-a twice was an independent protective factor for clinical pregnancy; the higher the normal morphological rate of the uterine JZ, the higher the pregnancy rate(P＜0.001).  
Conclusion  Three-dimensional vaginal ultrasound in the evaluation of the morphology of the uterine JZ is a good indicator for predicting the pregnancy outcome of FET in patients with adenomyosis, which provides reference for the number of GnRH-a times the patient used to improve pregnancy outcome.

Key words: adenomyosis, pregnancy, frozen embryo transfer