Intrauterine adhesion (IUA), a prevalent gynecological condition, has emerged as the primary etiology of uterine-related infertility, particularly in the context of rising rates of intrauterine surgical procedures (Lin et al., 2023). IUA arises due to trauma inflicted upon the endometrial tissue (Parashar et al., 2023), frequently associated with severe clinical manifestations that significantly compromise reproductive function, including menstrual irregularities, infertility, or recurrent pregnancy loss (Lee et al., 2021). Various therapeutic strategies have been investigated to mitigate its pathological characteristics, including transcervical resection of adhesions, intrauterine contraceptive devices, anti-adhesive barriers, and periodic hormonal therapies (Lin et al., 2023; Ai et al., 2020), with the advent of hysteroscopy facilitates the evolution of more sophisticated techniques for adhesiolysis under direct endoscopic visualization (Koythong and Guan, 2020).

Since its relation to infertility, IUA may have a impact on reproductive ability for women. Infertility stands as a pervasive and challenging global medical issue. It not only severely undermines the quality of life for couples and family wellbeing but also has implications for a nation’s medical standards and reproductive health (Priskorn et al., 2021). Key pregnancy-outcome factors include embryo quality, endometrial receptivity (ER), and embryo-endometrium sync. ER is crucial, referring to the endometrial state enabling blastocyst adhesion, invasion, and implantation for successful implantation (Zajicek et al., 2022). In detail, the endometrium, which encompasses the superior inner cortex as well as the mucosa, plays a pivotal role in fertility and the maintenance of reproductive health. In clinical practice, the assessment of endometrial thickness (ET) holds significant importance for the diagnosis of disorders associated with the endometrium (Mariani et al., 2021; Long et al., 2020; Wang et al., 2022). ET is frequently utilized as an indicator to assess ER. When the endometrium is excessively thin, it creates an unfavorable environment for embryonic implantation and subsequent development (Wang et al., 2022; Zhao et al., 2014). Endometrial pathological biopsy is conventionally regarded as the gold-standard method for assessing ER. However, its clinical utility is constrained due to its invasive nature. In contrast, ultrasound is more extensively utilized for ER evaluation (Costello et al., 2019; Ni et al., 2019). Up until now, three-dimensional ultrasound has gained extensive application in clinical medicine. It is capable of generating a continuous series of anatomical images, which are highly valuable for diagnostic purposes (Wang et al., 2022).

Given that existing research predominantly focuses on therapeutic strategies for IUA, there remains a critical gap in studies specifically investigating the ultrasound characteristics of ER in patients with IUA treated by transvaginal three-dimensional ultrasound following endometrial polyp surgery. This study systematically analyzes variations in ER parameters using three-dimensional ultrasound and their correlation with pregnancy outcomes, aiming to provide objective imaging evidence for optimizing postoperative fertility management in clinical practice.

The present study systematically evaluated the ultrasound characteristics of ER in patients with IUA following endometrial polyp surgery and their correlation with subsequent pregnancy outcomes. By comparing ultrasound-derived ER parameters with those of healthy controls and analyzing their association with subsequent pregnancy outcomes, we provide novel insights into the structural and functional alterations in the endometrium caused by IUA and their reproductive consequences.

Our findings indicate that patients with postoperative IUA exhibit significantly decreased ET and EV, along with reduced vascular indices—VI, FI, and (VFI—and elevated uterine artery impedance parameters—PI and RI. Moreover, patients with moderate and severe adhesions showed significantly reduced ET, EV, VI, FI, and VFI compared to those with mild adhesions, while RI and PI were notably increased. These changes were more pronounced in the severe group than in the moderate group, suggesting that increased adhesion severity is associated with poorer endometrial perfusion and receptivity. These findings highlight the utility of ultrasound parameters in stratifying IUA severity and guiding individualized treatment. These alterations reflect a compromised intrauterine environment, consistent with prior studies demonstrating that IUA, characterized by fibrotic adhesions within the uterine cavity, disrupt the endometrial architecture and impede angiogenesis, thereby limiting endometrial receptivity (Chen et al., 2023). As adequate vascular supply is a prerequisite for embryo implantation and early placental development, diminished blood perfusion may underlie the observed decline in reproductive potential.

Importantly, when stratified by pregnancy outcome during follow-up, patients in the pregnant subgroup demonstrated significantly more favorable ER parameters than those who failed to conceive. Specifically, they exhibited increased ET, EV, VI, FI, and VFI values, suggesting better-developed and more functional endometrial tissue with superior perfusion capacity. This aligns with previous findings showing that successful implantation is closely associated with higher subendometrial vascularity and volumetric indices (Peng et al., 2025; Wu et al., 2022). Interestingly, PI and RI were also higher in the pregnant group, potentially reflecting adaptive vascular remodeling rather than pathological resistance, highlighting the nuanced role of hemodynamics in implantation physiology.

Multivariate logistic regression further confirmed that ET, EV, PI, VI, and FI are independent predictors of pregnancy outcomes, reinforcing their clinical relevance. Notably, ROC analysis demonstrated that the combination of these parameters yielded superior predictive accuracy (AUC = 0.958) compared to any individual marker, supporting a multi-parametric assessment strategy. This finding is consistent with literature emphasizing the comprehensive nature of ER, which cannot be fully captured by a single measurement but instead requires integration of morphologic, hemodynamic, and functional dimensions (Craciunas et al., 2019).

Clinically, our results highlight the practical advantages of three-dimensional transvaginal ultrasound as a non-invasive, accessible, and reproducible tool for evaluating ER in patients with a history of endometrial pathology. Unlike invasive biopsy-based assessments, ultrasound allows real-time, cycle-specific monitoring, making it particularly suitable for fertility preservation and treatment planning (Elsokkary et al., 2019). In patients recovering from IUA, such dynamic evaluation enables timely identification of those at risk of poor reproductive outcomes, guiding tailored interventions such as hormonal modulation, intrauterine therapy, or assisted reproductive technologies.

This study has several limitations. First, it was conducted at a single center with a relatively limited sample size, which may limit the generalizability of the findings. Second, although we have provided a comparison of ultrasound parameters among IUA patients with different severity grades, the study did not include an inter-observer consistency analysis, which may introduce measurement bias. Third, the follow-up period was relatively short, and longer-term fertility outcomes after hysteroscopic treatment were not fully assessed. Future research should consider multicenter collaboration, larger sample sizes, inter-rater reliability testing, and extended follow-up to validate and expand upon these findings.

In conclusion, this study validates the clinical utility of three-dimensional ultrasound parameters in assessing ER status and predicting pregnancy outcomes in patients with IUA following endometrial polyp surgery. The integrated evaluation of structural, volumetric, and vascular ultrasound metrics provides a robust framework for optimizing reproductive counseling and therapeutic strategies in this challenging patient population. Future research should integrate advanced diagnostic modalities, such as contrast-enhanced ultrasonography or MRI, and explore molecular markers of endometrial receptivity to validate and extend our findings. Additionally, interventional trials leveraging ultrasound ER parameters to guide clinical decision-making could further strengthen causal inference.