Participants
As shown in the flow chart (Figure 1), 78 out of the 82 eligible patients gave informed consent and were included. Patients were divided into 2 groups according to their treatment of choice, 40 patients received insertion of LNG-IUD and 38 patients underwent a hysteroscopic niche resection. In the LNG-IUD group, 2 patients were excluded because of endometrial hyperplasia that was diagnosed postoperatively, 2 patients removed the LNG-IUD because of fertility desire, 36 patients finally completed the one-year follow-up and were included in the ITT analyses. Among these 36 patients, 1 patient removed the LNG-IUD for pelvic pain in the 2ndmonth, 1 patient removed the LNG-IUD for the partial expulsion in the 7th month. In the hysteroscopy group, 2 patients received LNG-IUD because of persisting bleeding symptoms in the 3.5th and 8th month respectively; 2 patients had an unintended pregnancy in the 7th, 8th month respectively, and then decided to continue the pregnancy; all 38 patients in the hysteroscopy group completed the one-year follow-up and were included in the ITT analyses.