Stress urinary incontinence (SUI) is a prevalent condition among elderly women, characterized by involuntary urination following increased abdominal pressure while the detrusor muscle of the bladder remains relaxed. Epidemiological studies have shown that the overall incidence of SUI in Chinese women over 20 years old is 18.9%, and gradually increases with age, with up to 27.4% in the 60–69 years old age group [1]. In the United States, the incidence of urinary incontinence among women ranges from 38.0% to 49.2%, with SUI accounting for more than half of these cases and the annual cost of treating female urinary incontinence is estimated to reach $12 billion [2, 3]. The manifestation of SUI symptoms not only poses serious risks to women’s health and quality of life but also significantly contributes to the social burden associated with this condition.

Apart from age, previous studies have identified various factors related to SUI symptoms, such as body weight, mode of delivery, number of pregnancies, physical activity, and chronic diseases [4, 5, 6, 7, 8]. In clinical practice, the intervention strategies for SUI symptoms differ based on severity; mild SUI typically involves conservative measures like pelvic floor muscle exercises, whereas moderate to severe cases may necessitate physical therapy or surgical intervention. Currently, the factors influencing the severity of SUI symptoms remain inadequately defined, and as the population ages, middle-aged and elderly women—who are particularly susceptible to SUI—have garnered increasing social attention.

In this study, we collected data on demographics, obstetric history, chronic diseases, and scores from the Urogenital Distress Inventory-6 (UDI-6) and the International Consultation on Incontinence Questionnaire-Short Form (ICIQ-SF) [9, 10]. Through both univariate and multivariate analyses, we aimed to identify factors associated with the severity of SUI symptoms in the elderly, thereby enhancing the diagnosis and treatment of this condition.

Trauma to the pelvic floor nerves and supporting tissues—such as the urethral sphincter, vaginal wall, supporting ligaments, and pelvic floor muscles—resulting from pregnancy and vaginal delivery is a significant contributor to SUI. Two prominent theories currently recognized in the pathogenesis of SUI are the “Hammock Theory” and the “Pressure Conduction Theory”. The “Hammock Theory” first proposed by DeLancey in 1994 [19], posits that the urinary tract (including the bladder neck and urethra) is supported by the intrapelvic fascia and anterior vaginal wall, with stability maintained by the pelvic fascial tendon arch and levator ani muscle. When the “hammock” structure weakens, the urethral closing pressure becomes insufficient to ensure normal urinary control, leading to symptoms of urinary leakage [19]. The “Pressure Conduction Theory” introduced by Enhorning in 1961 [20], emphasizes the importance of structural integrity in the urethra and pelvic floor support for effective urinary control. Following an injury to the pelvic floor support, urethral resistance diminishes, and as the pelvic floor support tissues relax, the proximal urethra descends. Consequently, increased abdominal pressure fails to be transmitted to the urethral tissue, resulting in greater pressure being exerted on the bladder. Eventually, this causes the bladder pressure to exceed urethral pressure, leading to involuntary urine overflow [20]. Additionally, estrogen deficiency is recognized as another mechanism contributing to the onset of SUI symptoms. The incidence of SUI in elderly women is significantly higher than that in younger women [1]. Research has demonstrated that ovarian removal reduces the thickness of the vaginal wall muscle layer and diminishes vaginal contractility, which may play a role in the pathogenesis of SUI [21].

Based on research into the pathogenesis and etiology of SUI, the data analyzed in this study included age, marital status, BMI, previous occupational status, pelvic floor muscle exercise status, years since menopause, maternal history, and chronic diseases, which encompassed a history of chronic cough, constipation, and hysterectomy. Multivariate logistic regression analysis revealed that age, the number of vaginal deliveries, chronic constipation, anterior vaginal wall prolapse, a history of postpartum urinary incontinence, and the morphology of the maximum urethral opening significantly influence the severity of SUI symptoms in elderly individuals.

As individuals age, the elasticity and resilience of the pelvic floor tissues may decline, leading to a reduced ability to adapt to changes in intra-abdominal pressure, which in turn increases the risk of developing SUI and exacerbates its severity. Constipation can contribute to an increase in intra-abdominal pressure, and it is often associated with dysfunction of the pelvic floor muscles. Prolonged constipation may result in excessive tension or fatigue of these muscles, thereby impairing their support for the urethra and heightening the risk of SUI while worsening its symptoms. Constipation is closely related to factors such as age and gender, particularly in women, where the incidence of constipation tends to rise with age, correlating with an increased prevalence of SUI [22]. Previous study has indicated a significant association between constipation and SUI, suggesting that management of constipation should be considered in the treatment of SUI to improve the overall symptoms experienced by patients.

The anterior vaginal wall is closely associated with changes in bladder position; thus, the correlation between anterior vaginal wall prolapse and the severity of SUI symptoms in elderly women may stem from a decrease in proximal urethral pressure caused by the downward movement of urethral tissue, which alters the mechanical dynamics of the pelvic floor [23]. Furthermore, the occurrence of urinary incontinence after childbirth may be linked to pelvic floor tissue damage sustained during pregnancy and delivery, which can directly impact the future development of urinary incontinence in elderly women [24].

Transperineal ultrasound examination is a straightforward and effective method for assessing pelvic floor structures. It allows for dynamic observation of changes in the bladder, urethra, and vagina under varying abdominal pressures, enabling the determination of related parameters [25]. In this study, we measured several key indicators using transperineal ultrasound, including the thickness of the detrusor muscle, the length of the perineal body, the mobility of the bladder neck, the angle of rotation of the urethra, the angle of the posterior bladder, and the distance from the lowest point of the bladder to the posterior margin of the pubic symphysis. Notably, there were no significant differences in these indicators between the mild SUI group and the moderate-to-severe SUI group (data not shown). As abdominal pressure increases, the inner urethral orifice undergoes spatial shifts during rest and maximum Valsalva maneuvers. Recent clinical study has indicated that the maximum opening of the inner urethral orifice in SUI patients often assumes a funnel shape under increased abdominal pressure, and this funnel shape is closely linked to urinary leakage symptoms [26]. In our study, we found that the shape of the maximum opening of the urethra was significantly associated with the severity of SUI symptoms in elderly women. Specifically, a funnel-shaped maximum opening of the urethra correlated with the occurrence of moderate to severe SUI symptoms. These changes in the maximum opening of the urethra are related to the process of pelvic pressure conduction, suggesting that this parameter could serve as an effective indicator for guiding SUI therapy.

As a prevalent condition among elderly women, the treatment of SUI varies depending on the severity of the disease. Investigating the factors associated with SUI severity and further exploring its pathogenesis may enhance the diagnosis and treatment of this condition. This study was a cross-sectional analysis that included a total of 394 elderly patients presenting with SUI symptoms in Wuhan, Hubei Province, China. The findings revealed that several factors—namely age, number of vaginal deliveries, chronic constipation, anterior vaginal wall prolapse, history of postpartum urinary incontinence, and a funnel-shaped maximum opening of the urethra—were strongly associated with increased severity of SUI symptoms. But cross-sectional studies have notable limitations, including the inability to establish causality, potential selection bias affecting generalizability, reliance on self-reported data leading to measurement bias, and a static perspective that fails to capture changes over time in the relationships between variables. Future research should aim to include a larger cohort from diverse regions to provide a more comprehensive analysis. Additionally, the completion of prospective studies is anticipated to further elucidate the etiological factors linked to the severity of SUI symptoms, thereby offering valuable clinical guidance.

This study identified several independent factors that significantly influence the severity of SUI symptoms in the elderly, including age, constipation, number of vaginal deliveries, anterior vaginal wall prolapse, history of postpartum urinary incontinence, and the shape of the maximum opening of the urethra. The findings of this study provide new directions for the prevention and management of SUI. By addressing risk factors associated with severe SUI symptoms—such as improving constipation, strengthening pelvic floor muscle exercises postpartum, and timely addressing anatomical issues in the pelvic floor—treatment efficacy can be significantly enhanced, ultimately promoting the overall health and quality of life for elderly patients affected by this condition.

All data points generated or analyzed during this study are included in this article, and there are no additional underlying data required to reproduce the results.

SuL, LH designed the research study. SuL, ZW and LY performed the research. LJ and ShL provided help and advice on the data collection. SuL analyzed the data. LH: funding support, project supervision. 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.

All procedures involving human participants were conducted in accordance with the ethical standards of the ethics committee of Renmin Hospital of Wuhan University (approval number: WDRY2020-K198) and adhered to the Declaration of Helsinki as revised in Tokyo in 2008. Written informed consent was obtained from all participants.

This study was funded by the National Natural Science Foundation of China (Project Approval No.: 82401896) and the Hubei Key Research and Development Program (Project Approval No.: 2022BCA045).

The authors declare no conflict of interest.