Comparing levonorgestrel intrauterine system versus hysteroscopic resection in patients with postmenstrual spotting related to a niche in the caesarean scar (MIHYS NICHE trial): protocol of a randomised controlled trial

IntroductionRecently, the rate of caesarean sections (CS) worldwide has risen and CS-associated complications such as niche have increased substantially. Until now, evidence-based clinical guidelines for the treatment of niche-related symptoms remain absent. In patients with postmenstrual spotting, it has not been studied if the effect of levonorgestrel 52 mg intrauterine system (LNG-IUS 52 mg) is superior to that of hysteroscopy. This study will answer the question of whether LNG-IUS 52 mg is more effective in improving postmenstrual spotting than hysteroscopic niche resection in women with niche-related spotting at 6 months after randomisation.Methods and analysisThis is a randomised controlled trial. A total of 208 women with postmenstrual spotting related to niche in the caesarean uterine scar of at least 2 mm and residual myometrium of at least 2.2 mm evaluated by MRI will be included. Women desiring to conceive within 1 year, with contraindications for LNG-IUS 52 mg or hysteroscopic surgery will be excluded. After informed consent is obtained, eligible women will be randomly allocated to LNG-IUS 52 mg or hysteroscopic niche resection at 1:1. The primary outcome is the efficacy in reducing postmenstrual spotting at 6 months after randomisation. The secondary outcomes include menstrual pattern, total days of blood loss per month, rate of amenorrhoea, side effects and complications.We will use a Visual Analogue Scale for chronic pelvic pain, urological symptoms and women’s satisfaction (five-point Likert scale).Ethics and disseminationThe study was approved by the local medical ethics committee and by the Institutional Review Board of the International Peace Maternity and Child Health Hospital, Shanghai, China (No. GKLW 2019-08). Participants will sign a written informed consent before participation. The results of this study will be submitted to a peer-reviewed journal for publication.Trial registration numberChiCTR1900025677.