Endometrial Polyps (EP) are gynecological diseases characterized by abnormal uterine bleeding, representing local overgrowth of stroma and endometrial glands. The prevalence of EP in different populations is 7.8%–34.9%, primarily diagnosed in women of childbearing age. While most are benign lesions, there’s a potential for malignancy. In the postmenopausal population, 4–6% of polyps are due to precancerous or malignant changes, and 1–2% of premenopausal patients are due to precancerous or malignant changes [1, 2, 3]. With the continuous improvement and development of hysteroscopy in the gynecological field, it has not only become the gold standard for diagnosing EP but is also widely recommended for the surgical treatment of symptomatic patients or those presenting with larger volumes, such as Transcervical Resection of Polyps (TCRP) under hysteroscopy [4, 5]. However, given the current uncertainty around the causes of EP onset and its potential for malignancy, there’s a notable risk of recurrence post-surgery. In recent years, the postoperative recurrence rate of endometrial polyps has been 2.5%–43.6%, depending on the follow-up time and the nature of the polyp. The risk of recurrence after surgery for non atypical proliferative polyps is higher than that for benign polyps (43.6% vs 8.3%, respectively), which affects the surgical outcome [6, 7]. Therefore, it is crucial to determine the risk factors post-TCRP to pinpoint and proactively intervene with high-risk individuals. To date, there is no existing research on personalized prediction of recurrence in women of reproductive age following TCRP. Nomograms, which are prediction model charts based on evidence-based medicine, can individually calculate the postoperative recurrence rate of a disease, offering high practicality [8], for example, application in endometriosis, cervical cancer, endometrial cancer, etc. [9, 10, 11]. In light of this, our study analyzes factors influencing the recurrence of TCRP in women of reproductive age, and constructs a nomogram to predict the recurrence after TCRP, aiming to assist in the early prevention and treatment of EP recurrence.

TCRP is the preferred treatment method for EP patients, with the advantages of accurate positioning and minimal trauma [13]. At the same time, it was found that the location and morphology of the polyps under direct hysteroscopy can be clearly displayed, the polyp base in the endometrial basal layer can be accurately removed, and the surrounding endometrial tissue is not damaged [14]. Although TCRP has obvious advantages, due to the strong regenerative ability of the endometrium, surgical treatment cannot fundamentally change the intrauterine environment. Therefore, there is a risk of polyp recurrence after surgery [15]. This study followed up women of childbearing age for two years after TCRP and found a recurrence rate of 10.93%, indicating a high risk of polyp recurrence in women of childbearing age after TCRP. Therefore, exploring the risk factors for recurrence in women of childbearing age after TCRP has important significance for improving the effect of TCRP and avoiding or reducing polyp recurrence.

In this study, factors such as age, BMI, polyp location, number of polyps, polyp diameter, gravidity, parity, uterine fibroids, endometriosis, and polycystic ovary syndrome were selected to analyze the relationship with the recurrence of women of childbearing age after TCRP. The results showed that BMI, polyp diameter, gravidity, and polycystic ovary syndrome are independent risk factors for recurrence in women of childbearing age after TCRP. However, this result cannot calculate the polyp recurrence rate of women of childbearing age after TCRP in a personalized way, and its practicality is relatively poor. The nomogram has the ability to predict individual clinical outcomes and has been applied to the recurrence of cervical dysplasia [8], recurrence after ischemic stroke [16], and recurrence after radiofrequency ablation in patients with non-valvular atrial fibrillation [17], with good results. Therefore, this study further introduced BMI, polyp diameter, gravidity, and polycystic ovary syndrome into R software to construct a nomogram for predicting the recurrence of polyps in women of childbearing age after TCRP, providing a relatively clear basis for personalized prevention and treatment of polyp recurrence.

The model developed in this study to predict the recurrence of polyps in women of childbearing age after TCRP shows that the nomogram score for those with a BMI $\ge$24 kg/m${}^2$ is 100 points higher than for those with a BMI 24 kg/m${}^2$, and patients with a BMI $\ge$24 kg/m${}^2$ have a higher recurrence rate. The reason may be when the BMI exceeds 24 kg/m${}^2$, especially in obese patients, the level of androgens in the body is often higher. The aromatase in adipose tissue can convert androgens into estrogens, and the more adipose tissue, the stronger its conversion ability, which leads to an excessive level of estrogen, thereby stimulating excessive growth of the endometrium and increasing the risk of polyp recurrence [18]. BMI is a controllable factor, so it is recommended that such patients should do appropriate exercise and eat a reasonable diet to control their weight within the normal range in order to reduce the recurrence of polyps after TCRP. The results of this study found that those with polycystic ovary syndrome have a nomogram score of 69.7 points higher than those without polycystic ovary syndrome, and the 2-year recurrence rate of patients with polycystic ovary syndrome is significantly higher than those without polycystic ovary syndrome. The possible mechanism is: long-term anovulation and the use of gonadotropins for ovulation induction treatment can cause an increase in estrogen levels, and patients often have abnormal glucose metabolism, which can easily stimulate the occurrence and development of EP. It has been reported that polyp diameter is related to successful pregnancy after hysteroscopic electrosection [19]. The results of this study found that those with a polyp diameter $\ge$2 cm have a nomogram score of 74.8 points higher than those with a polyp diameter 2 cm, and patients with a polyp diameter $\ge$2 cm have a higher recurrence rate. It is considered to be related to the larger the polyp diameter, the more severe the disease may be, which increases the risk of recurrence. Therefore, although polypectomy was performed using a residual free bipolar device and oral contraceptives were used after polypectomy, the high recurrence rate can be explained by the high number of polyp patients $\ge$2cm and high BMI. Similarly, Liu et al. [20] also found that BMI and polyp size are independent risk factors for recurrence after endometrial polypectomy. In addition, the results of this study also found that those with gravidity $\ge$3 times have a nomogram score of 80 points higher than those with gravidity 3 times, and compared with patients with gravidity 3 times, the 2-year recurrence rate of patients with gravidity $\ge$3 times has significantly increased. The reason may be that patients with more pregnancies, may have more births or abortions, which can easily lead to an increase in endometrial inflammatory reactions, thus causing EP. The internal verification of the nomogram model in this study found that the calibration curve slope for predicting the recurrence of women of childbearing age after TCRP is close to 1, the area under the ROC curve is 0.781 (95% CI = 0.6690.894), and the Hosmer-Lemeshow goodness of fit test $\chi$${}^2$ equals 8.720, with p = 0.366. The external verification results show that the calibration curve slope is close to 1, and the area under the ROC curve is 0.794 (95% CI = 0.705–0.883). This indicates that the nomogram for predicting the recurrence of women of childbearing age after TCRP has good accuracy and conformity, and has good application prospects. However, there are still deficiencies in this study, such as the limited number of patients included, and only 2 years of follow-up after surgery, which may affect the stability and predictive power of the nomogram. More cases and longer follow-up years need to be continued in future research.

In summary, the nomogram model constructed in this study based on BMI, polyp diameter, number of pregnancies, and polycystic ovary syndrome has good predictive power. It is beneficial for the early identification of high-risk groups for recurrence after TCRP in women of childbearing age. Targeted follow-up can be conducted on patients to be able to timely administer medication for treatment, thus preventing and reducing the risk of polyp recurrence. However, all the analysis variables in this study have only two values, and the contribution of each variable to polyp recurrence cannot be effectively evaluated. Moreover, patients who start taking oral contraceptives after hysteroscopic polypectomy may have a lower recurrence rate than expected, and the results may be limited because only symptomatic patients who underwent ultrasound examinations were included, potentially missing asymptomatic recurrences. In the next phase of research, it’s suggested to design experiments using larger sample sizes to obtain more accurate results.

The datasets used and/or analyzed during the present study are available from the corresponding author upon reasonable request.

XC and JL designed the research study. JL, HL, and NL collected the data. XC and NL analyzed the data. All authors contributed to editorial changes in the manuscript. All authors read and approved the final manuscript. All authors have participated sufficiently in the work and agreed to be accountable for all aspects of the work.

This retrospective study involving human participants adhered to the ethical standards of the institutional research committee and the 1964 Helsinki Declaration, including its later amendments or comparable ethical standards. The study received approval from Meizhou People’s Hospital ethics review board (approval number: 2022-C-126). All subjects provided their informed consent for inclusion before participating in the study.

We thank all of our colleagues working in the Department of Gynecology, Meizhou people’s Hospital.

This research received no external funding.

The authors declare no conflict of interest.