Short-term reproductive outcomes analysis and prediction of the modified uterine stent treatment for mild to moderate intrauterine adhesions: experience at a single institution

Intrauterine adhesions (IUAs), known as Asherman syndrome, have been first reported in 1894 [1]. It is the scarring disease in essence, characterized by uterine cavity narrowed and thin endometrium [2‐4]. IUAs may be associated with abnormal menstruation, recurrent pregnancy loss, secondary infertility, and pregnancy complications [5‐8]. In recent years, the incidence of IUAs has increased worldwide as a result of the high rate of induced abortion and the improvement of diagnostic techniques, such as three-dimensional ultrasonography and office hysteroscopy [9, 10].

Hysteroscopic adhesiolysis is the optimum route for treatment of IUAs [9, 11‐13]. However, the rate of recurrence is 30% to 66% [12‐14]. It is a knotty problem to prevent adhesion recurrence after surgery. To date, many approaches have become available, including cross-linked hyaluronic acid gel, balloon catheter and intrauterine device (IUD) [12, 15, 16]. There is still no consensus regarding the optimal postoperative treatment of IUAs [17]. In our hospital, IUAs has been treated with hysteroscopic procedures for more than 20 years. This retrospective study aimed to report our experience with a modified uterine stent placement under hysteroscopy treatment of mild-to-moderate IUAs and describe the short-term outcomes.

From October 2020 to March 2021, 142 patients underwent the whole procedures for eligibility without perforation, infection and other complications. 27 patients were excluded, because they suspended planning to have children. 115 patients (age 31.03±4.07 years, gravidity 2.77±1.48 times, Parity 0.43±0.58 times) were included in the analysis. Among them, the mild IUAs accounted for 18.26% (21/115), and the moderate IUAs accounted for 81.74% (94/115), respectively (Fig. 2).

After intrauterine surgery trauma, infection and other factors lead to the injury of the endometrial basal layer, the surface of the uterine cavity will appear lack of epithelial cell coverage, interstitial exposure, inflammatory cell infiltration and collagen deposition, which will lead to endometrial fibrosis and eventually intrauterine adhesions [19, 20]. Hysteroscopic adhesiolysis is the optimum route for treatment of IUAs [9, 11‐13]. To prevent adhesion recurrence after surgery, many approaches have been used in clinic, including amnion graft, cross-linked hyaluronic acid gel, IUD, estrogen therapy and so on [12, 15, 16]. It is reported that the rates of adhesion recurrence were 15.4%-48%, 13.4%-20.2%, 54.3% and 32.6%, respectively, in using amnion graft, cross-linked hyaluronic acid gel, IUD and estrogen therapy after hysteroscopic adhesiolysis [12, 21‐24].

Although the mild to moderate IUAs do not lead to amenorrhea, they often lead to repeated early pregnancy loss and even embryo implantation failure due to the characteristic of thin endometrium. Therefore, the patients with fertility requirement also need treatment. As we all know, the degree of adhesion may be aggravated after surgery if there is no effective measure to inhibit scar growth. So, gynecologist is usually cautious to perform surgery for the mild to moderate IUAs, especially for the marginal type of adhesions. In this study, adhesive tissues were separated followed a modified stent placement immediately. It has many potential advantages. Firstly, the endometrial thickness and endometrial volume significantly increased; Secondly, the rate of adhesion recurrence was only 13.04%, lower than that reported in the literatures [12, 21‐24]; Thirdly, the pregnancy rate in one year after stent removal was 86.09%, which was higher than those before reported [25‐27]. In addition, the operation is easy and convenient without thermal damage to the remaining endometrium [28]. Lastly, the modified stent was available and inexpensive in clinical. Finally, the modified uterine stent is composed of a stainless-steel metal ring and anti-adhesive membrane of Chitosan, which is partially biodegradable in three months and has good mechanical support properties. When placed in the uterine cavity, there is no inflammatory and immunogenic stimulation to the endometrium, and it can be used continuously to prevent uterine cavity contractures. Thus, the scheme of adhesiolysis with a modified stent to treat the mild to moderate IUAs is worth our attention.

In this study, we tried to predict the prognosis of patients by non-invasive ultrasonographic indicators. Which can reflect endometrial receptivity, including endometrial thickness, pattern and blood flow, endometrial echo, peristalsis, volume, and endometrial-myometrial junctional zone [29‐32]. It was limited reported in previous studies. We use ultrasound method making the endometrial thickness and endometrial volume numeric vectors, compared with hysteroscopy evaluation, ultrasound measurement endometrial thickness is more objective. It showed that endometrial thickness and volume might reflect the uterine cavity environment, especially the endometrial thickness after 3-months surgery. Because of the combination of antiadhesion membrane and metal ring, the stent can perfectly maintain the uterine cavity shape and inhibit scar contracture within 3 months after surgery. Therefore, it is not necessary to repeat hysteroscopy during this period, only to detect the endometrial thickness by ultrasonography to predict the recovery of the uterine cavity environment. However, when the anti-adhesion membrane is completely dissolved after 3 months, hysteroscopy should be performed in time to remove the bare metal ring that may affect growth of the endometrium or replace a new stent, possible new adhesions were also isolated at the same time. This series of procedures cannot be replaced by ultrasound examination. We suggest that it may attempt to use ultrasonography as a non-invasive method to follow up IUAs after surgery, reduce the number of repeated hysteroscopies. It is believed that with the progress of ultrasound equipment, non-invasive ultrasonographic prediction should be more accurate with more indicators including blood flow, endometrial echo, peristalsis and son on. Non-invasive monitoring after IUA surgery should be standardized.

At present, there is no effective biomedical material to promote endometrial repair and regeneration for the clinical treatment of intrauterine adhesions [19]. The main purpose of the modified stent is to maintain the uterine cavity shape as long as possible to inhibit scar growth until the endometrium itself functional regeneration. The stent does not appear to have the function to directly promote endometrium regeneration. However, we are pleased to discover a significant increase in endometrial thickness after stent placement and a pregnancy rate of 86.09% within one year. Future exploration will be to select suitable biodegradable materials to construct scaffolds or stent loaded with therapeutic drugs or stem cells to enhance endometrial regeneration.