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

INTRODUCTION: Recently, 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 ANALYSIS: This 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 DISSEMINATION: The 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 NUMBER: ChiCTR1900025677.