IUAs frequently occur in the endometrium and myometrium after endometrial basal layer injury. The repair process includes three transient overlapping periods: the inflammatory phase, the tissue formation phase, and the tissue remodeling period. In severe IUA cases, the basal layer of the endometrium is disrupted [11], leading to a decline in endometrial regeneration capability and receptivity. Therefore, it exerts negative effects on women’s fertility, and patients with IUAs are generally associated with a low pregnancy rate or infertility. Currently, hysteroscopy, which can effectively separate adhesions under direct vision, has become the gold standard for IUA treatment [8]. Notwithstanding, the recurrence rate remains high, especially in cases of severe IUAs. Postoperative uterine readhesion is a key factor affecting not only postoperative outcomes but also the postoperative pregnancy rate. Thus, it is imperative to enhance postoperative uterine repair and prevent postoperative recurrence of IUAs. At present, several techniques have been developed to prevent readhesion after intrauterine adhesion separation, encompassing intrauterine devices (IUDs), balloons, hyaluronic acid polymers, and estrogen [8].

In 1966, Dr. Polishuk undertook the first study on the prevention of intrauterine adhesions using IUDS after TCRA. He postulated that the intrauterine placement of an IUD for 2–3 months can effectively prevent intrauterine adhesions [13]. At present, the majority of clinicians endorse the use of intrauterine devices to prevent intrauterine readhesion. Indeed, the implantation of IUDs into the uterine cavity has become the standard method for preserving the uterine cavity and is often used to prevent adhesion formation. Moreover, IUD promotes physiological endometrial regeneration by separating the anterior and posterior uterine walls [14]. Following TCRA, endometrial repair usually requires 1–2 months; consequently, IUDs are routinely placed for 2–3 months. However, no universal consensus has been reached on the optimal duration for IUD placement after TCRA. Herein, IUD placement for both 1 month and 2 months yielded satisfactory outcomes in preventing adhesion recurrence. Besides, the AFS scores were significantly lower at the second hysteroscopy, whereas the endometrial thickness was significantly higher. It is worthwhile emphasizing that the decline in the AFS score was not significantly different between the two IUD groups. Similarly, no significant difference was noted in the degree of increase in endometrial thickness between the two groups. The pregnancy rates in the two groups were also similar. An IUD is a foreign body in the uterine cavity that may cause excessive inflammatory reactions. Long-term placement may also cause abnormal bleeding, intrauterine infection, IUD incarceration, and uterine perforation [15, 16]. In our study, participants from three groups had similar severity of adhesions considering the AFS Scores appeared no significant difference. And afer analyzing raw datas, there became a result signalling that the duration of IUD placement may be shortened to reduce the risk of complications without compromising efficiency.

Given the evolving understanding of the mechanisms underlying intrauterine adhesions, clinicians may also consider placing a 3–5 mL balloon post-TCRA to prevent intrauterine readhesion. Placing a balloon as well as an IUD can act as a barrier for fresh wounds [17]. The balloon is larger in volume and facilitates endometrial proliferation along its surface. Additionally, postoperative uterine exudate can be directed outward along the urethra, and the balloon can suppress hemostasis [11]. An RCT study reported that a 7-day IUD and balloon placement after TCRA demonstrated similar efficacy in the prevention of adhesion recurrence [9]. Our study compared the efficacy of a 5-day balloon placement for one month and an IUD placement for two months. Our results revealed that the reduction in the AFS score in the balloon group was higher than that in the IUD-1-month and IUD-2-month groups, indicating that balloon therapy is superior in restoring uterine morphology and volume and minimizing the recurrence of IUAs. Nevertheless, the improvement in endometrial thickness and the pregnancy rate were comparable among the three groups.

Nevertheless, the relevant mechanism is unclear. The IUD acts as a physical barrier between the walls of the uterus, keeping them separated during the healing process. This reduces the likelihood of the surfaces sticking together and forming new adhesions. Additionally, IUDs are made of copper, and experimental evidence suggests that copper can improve inflammation by reducing the production of reactive oxygen species (ROS). This may also be one of the mechanisms by which IUDs ameliorate IUA [18].

To conclude, placing a balloon or placing an IUD for one month or two months can effectively prevent adhesion recurrence and restore the shape of the uterine cavity. However, balloon placement outperformed IUD in terms of therapeutic effect. Moreover, the three groups exhibited a significant increase in endometrial thickness following TCRA, but the increase in endometrial thickness did not substantially differ among the three groups. In addition, although these treatments may partially prevent IUAs, the pregnancy outcomes remain suboptimal. Thus, there is an urgent need to optimize postoperative uterine repair, prevent the postoperative recurrence of IUAs, and enhance the reproductive prognosis of patients with IUAs.

However, there still remained several limits. First and foremost, our study was conducted in a single tertiary university hospital and the sample size was small, which may limit this study. To further enhance the level of evidence in the study results, additional randomized controlled studies are warranted. Beyond that, in terms of the procedures conducted in our study, we failed to measure parcitipants’ compliance and standardization to hormone therapy and report complications and adverse events in detail, which played a crucial part in analyzing the comprehensive benefits and risks from receiving IUD or balloon therapy. And at the end of the study, there is a lack of long-term follow up about development of offsprings and qualitative feedback from patients, accounting for important considerations in clinical decision-making. Finally, in the subsequent experiments, we will add a group undergoing standard treatment to provide a clearer understanding of the efficacy of this therapy.