Abstract
Objective: To identify the rate and the predictors of amenorrhea related to 1-year use of etonogestrel implant (ESI).  
Material and methods: It was a single-center; longitudinal study conducted at The Dairut Central Hospital, Assiut, Egypt from 1st of October 2021 to August 2023 included women who requested ESI for pregnancy prevention for at least 1 year. The rate of amenorrhea associated with 1-year use of ESI was reported. The changes of body mass index (BMI), the uterine and ovarian volume as well as the uterine blood flow during ESI use were also documented. Finally; the predictors associated with amenorrhea were also explored. The data were analyzed by Independent sample t-test, means of non-parametric tests and Chi-square test. Multivariate logistic regression was conducted to test for the predictors.
Results: Three hundred women were included in the study. The rate of amenorrhea at 1-year use of ESI was 38.6%. The predictive model found that fewer bleeding days, the shorter cycle, smaller uterine and ovarian volume, and higher uterine artery pulsatility index were significant predictors for amenorrhea at 1-year of ESI use. 
Conclusion: The ENG implant users have a significant rate of amenorrhea at 1-yer use. A significant increase in the BMI, decreases in the uterine and ovarian volume and the uterine blood flow were also observed. The woman should be counseled for the revealed predictors to increase the continuation and satisfaction rate.