Objective: To compare the effect of a hysteroscopic niche resection with a Levenorgestrel-releasing intrauterine device (LNG-IUD) on postmenstrual spotting in women with a symptomatic niche in the uterine cesarean scar. Design: Single center, prospective cohort study. Setting: A hospital affiliated to a medical college in China. Population: Women diagnosed with a niche by MRI scan and postmenstrual spotting of at least two days. Method: Women were allocated to two groups based on the shared medical decision-making approach, and were followed up for 1 year after treatment. Main outcome measures: The primary outcome was effectiveness in reducing postmenstrual spotting. Secondary outcomes were menstrual characteristics, direct medical costs, complications and side effects. Results: Effectiveness of LNG-IUD was significantly higher than a hysteroscopic niche resection during the first year, based on linear mixed models (P=0.009), and the effectiveness increased overtime within 1 year. Postmenstrual spotting reduced statistically in both groups. More slight side effects, although not statistically significant, were reported in LNG-LUD group at obviously lower direct medical costs. Conclusion：LNG-IUD is more effective in the treatment of postmenstrual spotting from the 6th month onwards than a hysteroscopic niche resection in women with a symptomatic niche at lower direct costs. Key Words：Niche, uterine cesarean scar, hysteroscopy niche resection, LNG-IUD, postmenstrual spotting, amenorrhea Tweetable abstract: LNG-IUD is more effective in the treatment of postmenstrual spotting related to a niche than hysteroscopic niche resection.