Strengths and Limitations
This study also had some limitations. First, some patients were lost to follow-up. Second, its single-center structure and provision of limited information on abnormal uterine bleeding symptoms prevented the long-term assessment of symptoms such as PMB. However, there were several strengths, including the implementation of a randomized controlled design, the use of one tertiary center entailing the same surgical techniques, the stipulation that all patients were undergoing their first CD, the double-blinded assessment procedure in which neither the physicians nor patients had knowledge about whether single- or double-layer closures were used, the examination of patients via SIS by two experienced sonographers, and the practice of waiting at least six months before conducting patient follow-ups, thus allowing sufficient tissue healing. Further, the sample size was calculated via power analysis based on niche and with a broad number of patients with 90% power. In addition, previous studies assessed CD scar defects only during the first three postoperative months or via transabdominal/TV USG, while many only presented RMT or niche results. As such, this study took niche and myometrial thickness measurements with multiple planes after at least six months based on the European Society for Gynaecological Endoscopy (ESGE) guidelines. Finally, previous studies accepted niche presence beginning at depths of 1mm, while this study required at least 2mm, thereby producing more specific results.