Comparing levonorgestrel intrauterine system with hysteroscopic niche resection in women with postmenstrual spotting related to a niche in the uterine cesarean scar: a randomized, open-label, controlled trial

Abstract

Postmenstrual spotting and chronic pelvic pain after cesarean delivery (CD) are associated with the presence of niches. Levonorgestrel intrauterine system (LNG-IUS 52 mg) and hysteroscopic niche resection have been shown to relieve niche-related symptoms six months after the intervention. This trial aimed to compare the effectiveness of LNG-IUS 52 mg with hysteroscopic niche resection in reducing niche-related postmenstrual spotting. This randomized, open-label, controlled trial was conducted at a medical center in Shanghai, China. Women with symptoms of postmenstrual spotting after CD, with a niche depth of at least 2 mm and residual myometrium of at least 2.2 mm on magnetic resonance imaging (MRI), and no intention to conceive within the next year were randomly assigned to receive treatment with LNG-IUS 52 mg or hysteroscopic niche resection. The primary outcome was the reduction in postmenstrual spotting 6 months after randomization, defined as the percentage of women with a reduction of at least 50% in spotting days from baseline. Efficacy and safety were assessed using intention-to-treat analysis. Between September 2019 and January 2022, 208 women were randomized into the LNG-IUS group (N=104) or the hysteroscopic niche resection group (N=104). At the 6th month follow-up, a 50% reduction in spotting had occurred in 78.4% (80/102) of women in the LNG-IUS group and in 73.1% (76/104) of women in the hysteroscopic niche resection group (RR=1.07, [95%CI 0.92-1.25]; P=0.370). Spotting decreased over time (Ptrend=0.001), with a stronger reduction being observed in the LNG-IUS group (P=0.001). There was also a significant interaction between time and treatment (P=0.007). From nine months onwards, a more significant reduction in spotting was observed in the LNG-IUS group than in the hysteroscopic niche resection group (9th month 89.2% vs. 72.1%, RR=1.24, [95% CI 1.08-1.42]; 12th month 90.2% vs. 70.2%, RR=1.29, [95% CI 1.12-1.48]). Moreover, compared with the hysteroscopic niche resection group, the LNG-IUS group had significantly fewer postmenstrual spotting days and total bleeding days from six months onwards (all P <0.001) as well as less pelvic pain from three months onwards (all P <0.010). No intervention-related complications were reported in any group. During follow-up, 11 (10.8%) women reported hormone-related side-effects and two women (2.0%) in the LNG-IUS group had spontaneous partial expulsion. Meanwhile, three unintended pregnancies were reported in the hysteroscopic niche resection group. In women with niche-related postmenstrual spotting, LNG-IUS was not more effective than hysteroscopic niche resection in reducing the number of spotting days by at least 50% at 6 months. However, the LNG-IUS was superior in reducing spotting from 9 months onwards, as it reduced the absolute number of spotting days from six months onwards and pelvic pain from three months onwards.