Strength and limitations
As far as we are aware of is this the first study comparing the effect of a hysteroscopic niche resection with LNG-IUD insertion on the reduction of spotting in women with a niche in the CS scar. The strength of our study is that we evaluated symptoms and side effects in a prospective and structured way using menstrual diaries. We had a homogeneous population due to the clear inclusion and exclusion criteria. Consecutive inclusion of patients, structured follow-up at four fixed evaluation points and the very low drop-out rate in both study groups reduce the risk on selection and verification bias.
However, our study has also some limitations. First, this study was divided into groups based on shared-medical decisions making this increases the risk on selection bias in comparison to a randomized design. This is underlined by the differences in age and in TRM between the two groups. Although additional analyses have shown that these variables were not related to the primary outcome. Due to the small sample size we were not able to study the effect of other potential confounders. Future randomized controlled studies of sufficient sample size should be carried out in the future to confirm our data.