Intracavitary Contrast-Enhanced Ultrasound Combined with Pelvic FloorUltrasound: A Real-Time, Non-Invasive, Radiation-Free Method for AssessingVesicovaginal Fistulas

Intracavitary Contrast-Enhanced Ultrasound Combined with Pelvic FloorUltrasound: A Real-Time, Non-Invasive, Radiation-Free Method for AssessingVesicovaginal Fistulas | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Intracavitary Contrast-Enhanced Ultrasound Combined with Pelvic FloorUltrasound: A Real-Time, Non-Invasive, Radiation-Free Method for AssessingVesicovaginal Fistulas Yelin Lou, Yang Hu, Tian Yang This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7473076/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 19 Jan, 2026 Read the published version in European Journal of Medical Research → Version 1 posted 11 You are reading this latest preprint version Abstract Objective To evaluate the diagnostic efficacy of transperineal pelvic floor ultrasound combined with intracavitary ultrasound in the assessment of vesicovaginal fistula (VVF). Methods A total of 17 patients suspected of VVF who were referred to Jinhua Central Hospital between March 2015 and May 2025 underwent transperineal pelvic floor ultrasonography using a three-dimensional intracavitary volumetric ultrasound probe. A 1:50 dilution of SonoVue contrast agent was injected into the bladder via catheter, and the presence of fistulous communication between the bladder and vagina was dynamically observed in two-dimensional harmonic imaging mode. Three- dimensional Render mode was used to reconstruct images for visualization of the fistula’s size, number, and anatomical location. In addition, three-dimensional ultrasound tomography was employed to measure the distance between the lateral opening of the bladder and the ureteral orifice of the VVF. The ultrasound findings were subsequently compared with surgical observations. Results Under intracavitary ultrasound with contrast enhancement, all 17 patients were diagnosed with VVF within 5–15 seconds of contrast injection, and all demonstrated an abnormal communication between the posterior wall of the bladder and the anterior wall of the vagina. All cases presented with a single VVF; 9 were located at the bladder neck or trigone, with a mean fistula diameter of 8.7 ± 4.9 mm. The mean distances from the VVF to the right and left ureteral openings were − 9.2 ± 2.3 mm and − 8.1 ± 2.1 mm, respectively, while the mean distance from the VVF to the bladder neck was 7.3 ± 1.7 mm. Among these, 8 cases were classified as high VVFs, with a mean fistula diameter of 10.4 ± 7.1 mm. The mean distances from the VVF to the right and left ureteral openings were 27.1 ± 14.0 mm and 28.8 ± 15.4 mm, respectively. No significant difference was observed between high and low VVFs in terms of distance from the left or right ureteral openings (P > 0.05). The ultrasound findings were consistent with intraoperative observations. Conclusion Transperineal pelvic floor ultrasound combined with intracavitary ultrasound provides accurate diagnosis and localization of VVF. The proposed four-step standardized ultrasound protocol demonstrates strong clinical applicability and potential for widespread adoption. Intracavitary Contrast-Enhanced Ultrasound Pelvic Floor Ultrasound Three-dimensional Vesicovaginal Fistulas Figures Figure 1 Figure 2 Introduction Vesicovaginal fistula (VVF) is an abnormal communication between the bladder and the vaginal wall, which leads to recurrent infections, emotional and psychological disturbances, and significantly impairs patients’ quality of life [1] . Recognized by the World Health Organization as a global public health issue, VVF imposes a substantial disease burden due to its high prevalence [2] . Evidence suggests that early and accurate diagnosis, along with timely intervention, is crucial for improving VVF prognosis [3] . In this study, we innovatively applied pelvic floor ultrasound combined with intracavitary contrast-enhanced ultrasound (IC-CEUS) to trace VVF using ultrasound contrast agents, aiming to reduce the rates of missed and misdiagnosed cases. Multiple three-dimensional ultrasound techniques were employed to evaluate the relationship between the fistula and surrounding anatomical structures. Furthermore, we established a standardized ultrasound evaluation system for VVF (Fig.1), which not only significantly enhanced diagnostic accuracy but also provided a reliable imaging basis for the development of individualized clinical treatment strategies. Methods This study retrospectively enrolled 17 patients with suspected VVF who were treated at the Department of Urology, Jinhua Hospital, School of Medicine, Zhejiang University, between March 2015 and May 2025. All patients presented with clinical symptoms of urinary leakage. The mean age was 53.1 ± 16.5 years, mean body mass index (BMI) was 22.8 ± 2.3 kg/m², and the mean preoperative disease duration was 13.0 ± 13.0 months. The etiology included surgery for pelvic- related diseases in 9 cases (5 cervical cancer, 2 uterine fibroids, 1 endometrial cancer, and 1 ovarian malignancy), adjuvant radiotherapy after radical cervical cancer treatment in 6 cases, and cesarean section injury in 2 cases. All patients underwent cystourethroscopy and vesicovaginal fistula repair for diagnostic confirmation. The study protocol was in accordance with the Declaration of Helsinki and was approved by the Ethics Committee of Jinhua Central Hospital. Experimental Setup and Data Collection A Voluson E10 ultrasound system (GE, USA) equipped with a low mechanical index mode was used, along with a RIC5-9-D intracavitary volumetric probe (frequency range: 5–9 MHz, sweep angle: 180°). The ultrasound contrast agent used was sulfur hexafluoride microbubbles (SonoVue, Bracco, Italy). According to the manufacturer’s instructions, 5 mL of saline was added to each vial, followed by thorough mixing to prepare the standard concentration, which was stored for subsequent use. For IC-CEUS, SonoVue was diluted with saline at a ratio of 1:50; the dilution could be adjusted as needed. Patients were placed in the lithotomy position. The intracavitary probe was covered with a disposable probe cover and positioned tightly against the perineum. Two-dimensional pelvic floor ultrasound was used to obtain a mid-sagittal section, clearly displaying the pubic symphysis, entire urethra, bladder, vagina, and cervix. Fan scanning was performed bilaterally to detect any potential fistulous echoes (Fig. 2A). For IC-CEUS, the diluted contrast agent was injected into the bladder via catheter, and real-time dynamic imaging was performed to observe any abnormal communication between the bladder and vagina, as well as its spatial relationship with the bladder trigone (Fig. 2B). In both harmonic and fundamental imaging modes, the region of interest was set at the internal urethral orifice, bladder, and vagina. Automatic volumetric scanning was performed to acquire three-dimensional ultrasound images, which were stored and analyzed using 4D View software. In harmonic mode, three-dimensional render mode was activated to generate stereoscopic images of the urethra, bladder, VVF fistula, and vagina (Fig. 2C). In fundamental mode, (TUI) was performed. From a series of parallel mid-sagittal pelvic floor sections, the plane that best visualized the VVF fistula was selected as the A-plane. A reference point was placed at the bladder-side opening of the VVF fistula, and the X-, Y-, and Z-axes were rotated to locate the bilateral ureteral orifices. Three-dimensional images showing the spatial relationship between the VVF bladder-side opening and the right and left ureteral orifices were stored. The distances between the VVF opening and the bilateral ureteral orifices were measured (Fig. 2D-E). The measurement was referenced to the interureteric ridge, with positive values indicating cephalic direction and negative values indicating caudal direction. All ultrasound examinations and measurements were performed by the same experienced pelvic floor sonographer. Cystoscopy was performed in all 17 patients. Of these, 9 underwent transperineal vesicovaginal fistula repair, and 8 underwent laparoscopic repair. Statistical Analysis Statistical analysis was performed using SPSS version 25.0. Normality of data distribution was assessed using the Kolmogorov–Smirnov test. Normally distributed continuous variables were expressed as mean ± standard deviation ( x̅± s ) and compared using independent samples t-tests. Non-normally distributed data were expressed as median and interquartile range [M (Q1–Q3)] and analyzed using the Mann–Whitney U test. Categorical variables were expressed as number and percentage [n (%)], and compared using the chi-square test. A P-value < 0.05 was considered statistically significant. Results Preoperative Pelvic Floor Ultrasound and IC-CEUS Findings Using two-dimensional pelvic floor ultrasound, a visible VVF lumen was detected in 9 out of 17 patients. Under IC-CEUS, an abnormal communication between the posterior wall of the bladder and the vagina was observed within 5–15 seconds after contrast agent injection in all 17 patients. All cases were diagnosed with VVF, and all presented with a single fistula. Among them, 9 cases were located at the bladder neck or trigone, with a mean fistula diameter of 8.7 ± 4.9 mm. The mean distances from the VVF to the right and left ureteral openings were − 9.2 ± 2.3 mm and − 8.1 ± 2.1 mm, respectively, while the mean distance from the VVF to the bladder neck was 7.3 ± 1.7 mm. In the remaining 8 cases, the VVF was located above the bladder trigone, with a mean fistula diameter of 10.4 ± 7.1 mm. The mean distances from the VVF to the right and left ureteral openings were 27.1 ± 14.0 mm and 28.8 ± 15.4 mm, respectively. There was no statistically significant difference between high and low VVFs in terms of distance from the left or right ureteral openings (P > 0.05) (Table 1). Surgical and Pathologic Results All 17 patients were confirmed to have VVF via cystourethroscopy. Among them, 9 cases were classified as low VVF (1 located at the bladder neck orifice and 8 at the bladder trigone), and 8 cases were classified as high VVF. Of the 9 patients with low VVF, 7 underwent repair using the Latzko method. All 8 patients with high VVF underwent repair using the same technique. Postoperative Pelvic Floor Ultrasound and IC-CEUS Results In 16 patients with successful surgical outcomes, the urinary catheter was left in place for 3–4 weeks postoperatively. Pelvic floor ultrasound and IC-CEUS showed no contrast leakage, confirming complete healing of the VVF fistula (Fig. 2F), after which the catheter was removed. Discussion VVFprimarily results from surgical injuries in obstetrics and gynecology, with its pathophysiological mechanism being ischemic necrosis of the organ wall. The predominant clinical manifestation is involuntary vaginal urine leakage, which is often misdiagnosed as urinary incontinence. Given the limited efficacy of conservative management, surgical repair remains the primary treatment option [ 4 ] . VVF repair surgery is technically challenging and requires a high level of operator skill and clinical experience [ 5 , 6 ] . Postoperative persistent urinary incontinence is a common complication, with reported incidence rates ranging from 4.3–67% across studies [ 7 – 11 ] . Therefore, a comprehensive preoperative evaluation of fistula characteristics—including number, size, location, and spatial relationships with adjacent structures—is crucial for optimizing surgical planning and outcomes. Currently, commonly used clinical diagnostic methods for VVF include the methylene blue staining test [ 12 ] , cystoscopy and colposcopy [ 3 , 13 – 15 ] , cystography [ 15 ] , ultrasound [ 16 ] , CT urography [ 17 ] , computer tomography urography (CTU), and magnetic resonance urography (MRU) [ 18 ] . However, these traditional methods have certain limitations. They often fail to accurately depict the location, size, and detailed anatomical relationships of the fistula, making the diagnosis of occult or small, tortuous fistulas particularly challenging and increasing the risk of misdiagnosis. Cystography and CT involve ionizing radiation and have relatively poor soft tissue resolution, and the use of iodinated contrast agents may trigger allergic reactions, limiting their use in patients with iodine allergies. Although MRI offers superior soft tissue resolution, its high cost and limited availability restrict its widespread clinical application [ 19 , 20 ] . In recent years, pelvic floor ultrasound has become the preferred imaging modality for assessing pelvic floor dysfunction in women due to its advantages of being noninvasive, radiation-free, high-resolution, and capable of real-time dynamic imaging [ 21 ] . However, conventional pelvic floor ultrasound has limited sensitivity in detecting microscopic fistulas, and certain rates of leakage and misdiagnosis still exist in clinical practice [ 22 ] . With advancements in ultrasound technology, IC-CEUS has emerged as a promising diagnostic tool. It enables clear visualization of tissue cavity anatomy through the tracing effect of microbubble contrast agents [ 23 – 25 ] . This technique leverages the scattering echo effect of ultrasound contrast agents to enhance the acoustic impedance difference between the cavity and surrounding tissues, thereby generating high-resolution contrast images. Clinically, SonoVue (Bracco, Italy), primarily composed of sulfur hexafluoride (SF6) gas microbubbles, is widely used due to its pulmonary metabolism, low allergenic potential, and high safety profile regarding hepatic and renal function [ 26 , 27 ] . As an innovative application of extravascular ultrasound, IC-CEUS utilizes low mechanical index harmonic imaging to visualize fistulas within 5–15 seconds after contrast injection. It combines the advantages of being radiation-free and enabling real-time dynamic imaging. A case report by Sun et al. confirmed that vesicovaginal fistulas could be successfully diagnosed using intravesical injection of SonoVue via a catheter [ 28 ] . Compared with cystography, IC-CEUS can use both fundamental and harmonic imaging modes to dynamically display pelvic floor soft tissue images in synchronization with contrast flow, offering superior spatial resolution and real-time feedback. In this study, only 9 out of 17 suspected VVF cases were detected using two-dimensional pelvic floor ultrasound, whereas IC-CEUS successfully identified all 17 cases. One patient with post-cesarean VVF was initially undiagnosed by conventional cystoscopy due to the small size of the fistula and only a localized mucosal elevation. However, IC-CEUS, with its microbubble tracer capability, clearly delineated the fistula, demonstrating its clinical value in detecting subtle lesions. This technological advantage provided a solid foundation for the methodological innovation in this study. In this study, an intracavitary three-dimensional volumetric probe was used in combination with transperineal pelvic floor ultrasound. Compared with abdominal probes, intracavitary high-frequency ultrasound (probe frequency: 5–9 MHz) offers superior resolution of the microstructures of the bladder, vagina, and surrounding lesions [ 29 ] . Conventional transperineal ultrasound often fails to clearly visualize high VVFs. However, the use of an endoluminal probe in this study allowed for closer proximity to the target VVF, resulting in clearer imaging. In IC-CEUS two- dimensional mode, the image orientation was flipped to align with the anatomical position of the patient in the standing position. In three-dimensional Render mode, the system generated images comparable to CT reconstructions, clearly depicting the spatial relationships among the urethra, bladder, vagina, and VVF, thereby enhancing clinical interpretability [ 30 ] . The key aspects of VVF surgery include locating the fistula, assessing its size, number, and location, and evaluating its relationship with the bilateral ureteral orifices to determine the optimal surgical approach. When the fistula is clearly visualized and the vaginal condition is favorable, low VVFs (fistula located in the bladder trigone) are typically managed via a transperineal approach. In contrast, high VVFs (fistula located above the bladder trigone), which are more likely to involve the ureters, are better suited for a transabdominal approach. In this study, IC-CEUS was first used to accurately localize the VVF site. Subsequently, pelvic floor three-dimensional ultrasound was employed to acquire volumetric images of the region of interest. Using TUI technology, three orthogonal planes (A, B, and C) were reconstructed, enabling intuitive three-dimensional visualization of the pelvic floor structures. This technique clearly displayed the tissue echoes of the bladder, VVF, and vagina, and precisely localized the bladder-side openings of the VVF. It also enabled visualization of the relative positions of the bilateral interureteric ridge and ureteral orifices, allowing classification of VVFs into high (fistula located above the ureteral ridge) and low (fistula located below the ridge in the bladder trigone). The distances between the fistula openings and the bilateral interureteric ridges were measured to provide critical information for surgical planning and risk assessment—an advantage unique to this technique. Furthermore, this study established a four-step standardized operating procedure (SOP) for VVF diagnosis (Fig. 1): (a) Perform left and right fan scanning using two- dimensional pelvic floor ultrasound in the mid-sagittal plane. (b) In intracavitary ultrasound mode, dynamically observe the presence or absence of a vesicovaginal fistula. (c) In harmonic mode, use three-dimensional Render mode to obtain a stereoscopic image of the VVF. (d) In fundamental mode, apply three-dimensional TUI to measure the distances between the bladder-side opening of the VVF and the bilateral ureteral orifices and the bladder neck. The results of this study confirm that IC-CEUS offers significant advantages in the diagnosis of VVF, with diagnostic accuracy markedly superior to that of traditional imaging modalities. Research on the application of IC-CEUS in VVF diagnosis remains limited. Based on our findings, IC-CEUS—being noninvasive, radiation-free, and capable of real-time dynamic imaging—not only enables precise localization of the fistula and assessment of its three-dimensional spatial relationships but also allows for quantitative measurement of distances between the fistula and key anatomical landmarks. These capabilities provide a robust foundation for clinical decision-making. Future research should focus on establishing standardized operating protocols, developing intelligent auxiliary diagnostic systems, and exploring surgical navigation applications. Advancements in these areas will further enhance the overall diagnosis and treatment of VVF and ultimately improve patient outcomes. Table 1 VVF Related Parameters High position Low position P Number of cases 8 9 / Fistula diameter(mm) 10.4 ± 7.1 8.7 ± 4.9 0.58 Distance between VVF and left ureteral opening(mm) 28.8 ± 15.4 -8.1±-2.1 0.003 Distance between VVF and right ureteral opening(mm) 27.1 ± 14.0 -9.2±-2.3 0.003 Distance between VVF and bladder neck opening(mm) / 7.3 ± 1.7 / Abbreviations VVF vesicovaginal fistula IC-CEUS intracavitary contrast-enhanced ultrasound BMI body mass index TUI three-dimensional tomographic ultrasound imaging CTU computer tomography urography MRU magnetic resonance urography SOP standardized operating procedure BL bladder U urethra V vagina RU right ureteral orifice LU left ureteral orifice AN anterior UP superior PO posterior DOWN Inferior Declarations Acknowledgements The authors would like to thank everyone who contributed to our study especially staff from the Urology Department, Hospital Jinhua. Author contributions Yelin Lou drafted and revised the manuscript.Tian Yang collected the data and performed the statistical analysis. Yang Hu conceived and revised this study. Funding This work was supported by the Zhejiang Province Medical and Healthy Technology Project (2025KY1747); Data availability The data that support the findings of this study are available from the cor responding author upon reasonable request. Ethics approval and consent to participate This study was approved by the the Ethics Committee of Jinhua Central Hospital (Ethics Review No 52 of 2018). Informed consent was obtained from the participants or their legal representatives. Consent for publication Not applicable. Competing interests The authors declare no competing interests. Author details 1Department of Ultrasonography, Affiliated Jinhua Hospital, Zhejiang University School of Medicine，Jinhua Municipal Central Hospital, Jinhua 321000, China； 2Department of Urology, Affiliated Jinhua Hospital Zhejiang University School of Medicine，Jinhua Municipal Central Hospital, Jinhua 321000, China； 3Department of Ultrasonography, Jinhua Maternal and Child Health Hospital, Jinhua 321000, China； References Randazzo M, Lengauer L, Rochat C-H, Ploumidis A, Kröpfl D, Rassweiler J, et al. Best Practices in Robotic-assisted Repair of Vesicovaginal Fistula: A Consensus Report from the European Association of Urology Robotic Urology Section Scientific Working Group for Reconstructive Urology. Eur Urol. 2020;78:432–42. Wall LL. Obstetric vesicovaginal fistula as an international public-health problem. Lancet. 2006;368:1201–9. Chinthakanan O, Sirisreetreerux P, Saraluck A. Vesicovaginal Fistulas: Prevalence, Impact, and Management Challenges. Medicina (Kaunas). 2023;59:1947. 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Cite Share Download PDF Status: Published Journal Publication published 19 Jan, 2026 Read the published version in European Journal of Medical Research → Version 1 posted Editorial decision: Revision requested 25 Nov, 2025 Reviews received at journal 03 Nov, 2025 Reviews received at journal 25 Oct, 2025 Reviews received at journal 24 Oct, 2025 Reviewers agreed at journal 20 Oct, 2025 Reviewers agreed at journal 18 Oct, 2025 Reviewers agreed at journal 10 Oct, 2025 Reviewers invited by journal 07 Oct, 2025 Editor assigned by journal 08 Sep, 2025 Submission checks completed at journal 02 Sep, 2025 First submitted to journal 27 Aug, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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Hu","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA40lEQVRIie3RIQvCQBTA8afBtLEmG4b7Cjesol9lY2AyGA2GCbIkWifidxAsxjceLJ1dUFAQTIaBIAYRTwWjO5vg/ctdeD+44wHodL+YDYCP0wJCzDrfEKeX+kksFMkzTqJKZl9BsMnAJaO7qY8jkaEZArPK+JnwjeBkpIdgZCxn6CzAHU+8HGK3JClR4MSSuAI8vs4hLH6QGwV8e9yhHykQWEliRlTnKAATFcJXzXYyHZLnhClPQmHn/4XFwTw7nqkhV7k/XTs1ZlXyHiYrGgB++LrbHyffFS4ADbVRnU6n+8vumvxT0zoyjqYAAAAASUVORK5CYII=","orcid":"","institution":"Jinhua Central Hospital","correspondingAuthor":true,"prefix":"","firstName":"Yang","middleName":"","lastName":"Hu","suffix":""},{"id":531848674,"identity":"b9a65ff8-10e6-4973-8f94-c2e59495659f","order_by":2,"name":"Tian Yang","email":"","orcid":"","institution":"Jinhua Central Hospital","correspondingAuthor":false,"prefix":"","firstName":"Tian","middleName":"","lastName":"Yang","suffix":""}],"badges":[],"createdAt":"2025-08-27 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09:44:23","extension":"xml","order_by":7,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":70312,"visible":true,"origin":"","legend":"","description":"","filename":"2b490dec3cfb4d7990d99366d16861881structuring.xml","url":"https://assets-eu.researchsquare.com/files/rs-7473076/v1/4ffed19e13f841ee9feed3a5.xml"},{"id":93921380,"identity":"9afe9242-86e8-4ce8-a9a6-84ce85a8e485","added_by":"auto","created_at":"2025-10-20 09:44:23","extension":"html","order_by":8,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":79312,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-7473076/v1/e8ef7fbb17c31eaf2c26a433.html"},{"id":93921374,"identity":"14f65db1-0a3a-4037-aa71-117b0929f3c5","added_by":"auto","created_at":"2025-10-20 09:44:22","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":180117,"visible":true,"origin":"","legend":"\u003cp\u003eVVF Diagnosis Four-step SOP\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-7473076/v1/5d60122ba8e02fedea743bce.png"},{"id":93921375,"identity":"d989ba05-c44d-4315-9115-efcdffaec309","added_by":"auto","created_at":"2025-10-20 09:44:23","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":715560,"visible":true,"origin":"","legend":"\u003cp\u003eFour-step ultrasound SOP for vesicovaginal fistula evaluation.\u003c/p\u003e\n\u003cp\u003eA: Perform left/right fan scanning with 2D pelvic floor ultrasound in mid-sagittal plane.\u003c/p\u003e\n\u003cp\u003eB: Assess dynamically for vesicovaginal fistula under contrast-enhanced endoluminal ultrasound.\u003c/p\u003e\n\u003cp\u003eC: Use 3D Render mode in harmonic mode to obtain stereoscopic VVF image.\u003c/p\u003e\n\u003cp\u003eD E: Apply 3D TUI in fundamental mode to measure distances from VVF bladder opening to bilateral ureteral orifices and bladder neck.\u003c/p\u003e\n\u003cp\u003eF: Postoperative contrast-enhanced ultrasound showed fistula resolution.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-7473076/v1/7e57e2a272f5d7f22a6aa7fe.png"},{"id":101151724,"identity":"1987260e-9a0c-45fa-ae3a-09a8c1b16c2a","added_by":"auto","created_at":"2026-01-26 16:03:09","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1529062,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7473076/v1/9f6a027c-c642-44db-9233-2b8114480509.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Intracavitary Contrast-Enhanced Ultrasound Combined with Pelvic FloorUltrasound: A Real-Time, Non-Invasive, Radiation-Free Method for AssessingVesicovaginal Fistulas","fulltext":[{"header":"Introduction","content":"\u003cp\u003eVesicovaginal fistula (VVF) is an abnormal communication between the bladder and the vaginal wall, which leads to recurrent infections, emotional and psychological disturbances, and significantly impairs patients\u0026rsquo; quality of life \u003csup\u003e[1]\u003c/sup\u003e. Recognized by the World Health Organization as a global public health issue, VVF imposes a substantial disease \u0026nbsp;burden \u0026nbsp;due \u0026nbsp; to \u0026nbsp;its \u0026nbsp;high \u0026nbsp; prevalence \u0026nbsp;\u003csup\u003e[2]\u003c/sup\u003e. Evidence suggests that early and accurate \u0026nbsp;diagnosis, \u0026nbsp;along \u0026nbsp; with \u0026nbsp;timely \u0026nbsp;intervention, \u0026nbsp; is crucial for improving VVF prognosis\u0026nbsp;\u003csup\u003e[3]\u003c/sup\u003e. In this study, we innovatively applied pelvic floor ultrasound combined with intracavitary contrast-enhanced ultrasound (IC-CEUS) to trace VVF using ultrasound contrast agents, aiming to reduce the rates of missed and misdiagnosed cases. Multiple three-dimensional ultrasound techniques were employed to evaluate the relationship between the fistula and surrounding anatomical structures. Furthermore, we established a standardized ultrasound evaluation system for VVF (Fig.1), which not only significantly enhanced diagnostic accuracy but also provided a reliable imaging basis for the development of individualized clinical treatment strategies.\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003eThis study retrospectively enrolled 17 patients with suspected VVF who were treated at the Department of Urology, Jinhua Hospital, School of Medicine, Zhejiang University, between March 2015 and May 2025. All patients presented with clinical symptoms of urinary leakage. The mean age was 53.1\u0026thinsp;\u0026plusmn;\u0026thinsp;16.5 years, mean body mass index (BMI) was 22.8\u0026thinsp;\u0026plusmn;\u0026thinsp;2.3 kg/m\u0026sup2;, and the mean preoperative disease duration was 13.0\u0026thinsp;\u0026plusmn;\u0026thinsp;13.0 months. The etiology included surgery for pelvic- related diseases in 9 cases (5 cervical cancer, 2 uterine fibroids, 1 endometrial cancer, and 1 ovarian malignancy), adjuvant radiotherapy after radical cervical cancer treatment in 6 cases, and cesarean section injury in 2 cases. All patients underwent cystourethroscopy and vesicovaginal fistula repair for diagnostic confirmation. The study protocol was in accordance with the Declaration of Helsinki and was approved by the Ethics Committee of Jinhua Central Hospital.\u003c/p\u003e\n\u003ch3\u003eExperimental Setup and Data Collection\u003c/h3\u003e\n\u003cp\u003eA Voluson E10 ultrasound system (GE, USA) equipped with a low mechanical index mode was used, along with a RIC5-9-D intracavitary volumetric probe (frequency range: 5\u0026ndash;9 MHz, sweep angle: 180\u0026deg;). The ultrasound contrast agent used was sulfur hexafluoride microbubbles (SonoVue, Bracco, Italy). According to the manufacturer\u0026rsquo;s instructions, 5 mL of saline was added to each vial, followed by thorough mixing to prepare the standard concentration, which was stored for subsequent use. For IC-CEUS, SonoVue was diluted with saline at a ratio of 1:50; the dilution could be adjusted as needed.\u003c/p\u003e\u003cp\u003ePatients were placed in the lithotomy position. The intracavitary probe was covered with a disposable probe cover and positioned tightly against the perineum. Two-dimensional pelvic floor ultrasound was used to obtain a mid-sagittal section, clearly displaying the pubic symphysis, entire urethra, bladder, vagina, and cervix. Fan scanning was performed bilaterally to detect any potential fistulous echoes (Fig.\u0026nbsp;2A). For IC-CEUS, the diluted contrast agent was injected into the bladder via catheter, and real-time dynamic imaging was performed to observe any abnormal communication between the bladder and vagina, as well as its spatial relationship with the bladder trigone (Fig.\u0026nbsp;2B). In both harmonic and fundamental imaging modes, the region of interest was set at the internal urethral orifice, bladder, and vagina. Automatic volumetric scanning was performed to acquire three-dimensional ultrasound images, which were stored and analyzed using 4D View software. In harmonic mode, three-dimensional render mode was activated to generate stereoscopic images of the urethra, bladder, VVF fistula, and vagina (Fig.\u0026nbsp;2C). In fundamental mode, (TUI) was performed. From a series of parallel mid-sagittal pelvic floor sections, the plane that best visualized the VVF fistula was selected as the A-plane. A reference point was placed at the bladder-side opening of the VVF fistula, and the X-, Y-, and Z-axes were rotated to locate the bilateral ureteral orifices. Three-dimensional images showing the spatial relationship between the VVF bladder-side opening and the right and left ureteral orifices were stored. The distances between the VVF opening and the bilateral ureteral orifices were measured (Fig.\u0026nbsp;2D-E). The measurement was referenced to the interureteric ridge, with positive values indicating cephalic direction and negative values indicating caudal direction. All ultrasound examinations and measurements were performed by the same experienced pelvic floor sonographer.\u003c/p\u003e\u003cp\u003eCystoscopy was performed in all 17 patients. Of these, 9 underwent transperineal vesicovaginal fistula repair, and 8 underwent laparoscopic repair.\u003c/p\u003e\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003eStatistical Analysis\u003c/h2\u003e\u003cp\u003eStatistical analysis was performed using SPSS version 25.0. Normality of data distribution was assessed using the Kolmogorov\u0026ndash;Smirnov test. Normally distributed continuous variables were expressed as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation ( x̅\u0026plusmn;\u0026thinsp;s ) and compared using independent samples t-tests. Non-normally distributed data were expressed as median and interquartile range [M (Q1\u0026ndash;Q3)] and analyzed using the Mann\u0026ndash;Whitney U test. Categorical variables were expressed as number and percentage [n (%)], and compared using the chi-square test. A P-value\u0026thinsp;\u0026lt;\u0026thinsp;0.05 was considered statistically significant.\u003c/p\u003e\u003c/div\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec5\" class=\"Section2\"\u003e\u003ch2\u003ePreoperative Pelvic Floor Ultrasound and IC-CEUS Findings\u003c/h2\u003e\u003cp\u003eUsing two-dimensional pelvic floor ultrasound, a visible VVF lumen was detected in 9 out of 17 patients. Under IC-CEUS, an abnormal communication between the posterior wall of the bladder and the vagina was observed within 5\u0026ndash;15 seconds after contrast agent injection in all 17 patients. All cases were diagnosed with VVF, and all presented with a single fistula. Among them, 9 cases were located at the bladder neck or trigone, with a mean fistula diameter of 8.7\u0026thinsp;\u0026plusmn;\u0026thinsp;4.9 mm. The mean distances from the VVF to the right and left ureteral openings were \u0026minus;\u0026thinsp;9.2\u0026thinsp;\u0026plusmn;\u0026thinsp;2.3 mm and \u0026minus;\u0026thinsp;8.1\u0026thinsp;\u0026plusmn;\u0026thinsp;2.1 mm, respectively, while the mean distance from the VVF to the bladder neck was 7.3\u0026thinsp;\u0026plusmn;\u0026thinsp;1.7 mm. In the remaining 8 cases, the VVF was located above the bladder trigone, with a mean fistula diameter of 10.4\u0026thinsp;\u0026plusmn;\u0026thinsp;7.1 mm. The mean distances from the VVF to the right and left ureteral openings were 27.1\u0026thinsp;\u0026plusmn;\u0026thinsp;14.0 mm and 28.8\u0026thinsp;\u0026plusmn;\u0026thinsp;15.4 mm, respectively. There was no statistically significant difference between high and low VVFs in terms of distance from the left or right ureteral openings (P\u0026thinsp;\u0026gt;\u0026thinsp;0.05) (Table\u0026nbsp;1).\u003c/p\u003e\u003c/div\u003e\n\u003ch3\u003eSurgical and Pathologic Results\u003c/h3\u003e\n\u003cp\u003eAll 17 patients were confirmed to have VVF via cystourethroscopy. Among them, 9 cases were classified as low VVF (1 located at the bladder neck orifice and 8 at the bladder trigone), and 8 cases were classified as high VVF. Of the 9 patients with low VVF, 7 underwent repair using the Latzko method. All 8 patients with high VVF underwent repair using the same technique.\u003c/p\u003e\n\u003ch3\u003ePostoperative Pelvic Floor Ultrasound and IC-CEUS Results\u003c/h3\u003e\n\u003cp\u003eIn 16 patients with successful surgical outcomes, the urinary catheter was left in place for 3\u0026ndash;4 weeks postoperatively. Pelvic floor ultrasound and IC-CEUS showed no contrast leakage, confirming complete healing of the VVF fistula (Fig.\u0026nbsp;2F), after which the catheter was removed.\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eVVFprimarily results from surgical injuries in obstetrics and gynecology, with its pathophysiological mechanism being ischemic necrosis of the organ wall. The predominant clinical manifestation is involuntary vaginal urine leakage, which is often misdiagnosed as urinary incontinence. Given the limited efficacy of conservative management, surgical repair remains the primary treatment option \u003csup\u003e[\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]\u003c/sup\u003e. VVF repair surgery is technically challenging and requires a high level of operator skill and clinical experience \u003csup\u003e[\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]\u003c/sup\u003e. Postoperative persistent urinary incontinence is a common complication, with reported incidence rates ranging from 4.3\u0026ndash;67% across studies \u003csup\u003e[\u003cspan additionalcitationids=\"CR8 CR9 CR10\" citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]\u003c/sup\u003e. Therefore, a comprehensive preoperative evaluation of fistula characteristics\u0026mdash;including number, size, location, and spatial relationships with adjacent structures\u0026mdash;is crucial for optimizing surgical planning and outcomes.\u003c/p\u003e\u003cp\u003eCurrently, commonly used clinical diagnostic methods for VVF include the methylene blue staining test \u003csup\u003e[\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]\u003c/sup\u003e, cystoscopy and colposcopy \u003csup\u003e[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan additionalcitationids=\"CR14\" citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]\u003c/sup\u003e, cystography \u003csup\u003e[\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]\u003c/sup\u003e, ultrasound \u003csup\u003e[\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]\u003c/sup\u003e, CT urography \u003csup\u003e[\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]\u003c/sup\u003e, computer tomography urography (CTU), and magnetic resonance urography (MRU) \u003csup\u003e[\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]\u003c/sup\u003e. However, these traditional methods have certain limitations. They often fail to accurately depict the location, size, and detailed anatomical relationships of the fistula, making the diagnosis of occult or small, tortuous fistulas particularly challenging and increasing the risk of misdiagnosis. Cystography and CT involve ionizing radiation and have relatively poor soft tissue resolution, and the use of iodinated contrast agents may trigger allergic reactions, limiting their use in patients with iodine allergies. Although MRI offers superior soft tissue resolution, its high cost and limited availability restrict its widespread clinical application \u003csup\u003e[\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e, \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e\u003cp\u003eIn recent years, pelvic floor ultrasound has become the preferred imaging modality for assessing pelvic floor dysfunction in women due to its advantages of being noninvasive, radiation-free, high-resolution, and capable of real-time dynamic imaging \u003csup\u003e[\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]\u003c/sup\u003e. However, conventional pelvic floor ultrasound has limited sensitivity in detecting microscopic fistulas, and certain rates of leakage and misdiagnosis still exist in clinical practice \u003csup\u003e[\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]\u003c/sup\u003e. With advancements in ultrasound technology, IC-CEUS has emerged as a promising diagnostic tool. It enables clear visualization of tissue cavity anatomy through the tracing effect of microbubble contrast agents \u003csup\u003e[\u003cspan additionalcitationids=\"CR24\" citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]\u003c/sup\u003e. This technique leverages the scattering echo effect of ultrasound contrast agents to enhance the acoustic impedance difference between the cavity and surrounding tissues, thereby generating high-resolution\u003c/p\u003e\u003cp\u003econtrast images. Clinically, SonoVue (Bracco, Italy), primarily composed of sulfur hexafluoride (SF6) gas microbubbles, is widely used due to its pulmonary metabolism, low allergenic potential, and high safety profile regarding hepatic and renal function \u003csup\u003e[\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e, \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e\u003cp\u003eAs an innovative application of extravascular ultrasound, IC-CEUS utilizes low mechanical index harmonic imaging to visualize fistulas within 5\u0026ndash;15 seconds after contrast injection. It combines the advantages of being radiation-free and enabling real-time dynamic imaging. A case report by Sun et al. confirmed that vesicovaginal fistulas could be successfully diagnosed using intravesical injection of SonoVue via a catheter \u003csup\u003e[\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]\u003c/sup\u003e. Compared with cystography, IC-CEUS can use both fundamental and harmonic imaging modes to dynamically display pelvic floor soft tissue images in synchronization with contrast flow, offering superior spatial resolution and real-time feedback. In this study, only 9 out of 17 suspected VVF cases were detected using two-dimensional pelvic floor ultrasound, whereas IC-CEUS successfully identified all 17 cases. One patient with post-cesarean VVF was initially undiagnosed by conventional cystoscopy due to the small size of the fistula and only a localized mucosal elevation. However, IC-CEUS, with its microbubble tracer capability, clearly delineated the fistula, demonstrating its clinical value in detecting subtle lesions. This technological advantage provided a solid foundation for the methodological innovation in this study.\u003c/p\u003e\u003cp\u003eIn this study, an intracavitary three-dimensional volumetric probe was used in combination with transperineal pelvic floor ultrasound. Compared with abdominal probes, intracavitary high-frequency ultrasound (probe frequency: 5\u0026ndash;9 MHz) offers superior resolution of the microstructures of the bladder, vagina, and surrounding lesions \u003csup\u003e[\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]\u003c/sup\u003e. Conventional transperineal ultrasound often fails to clearly visualize high VVFs. However, the use of an endoluminal probe in this study allowed for closer proximity to the target VVF, resulting in clearer imaging. In IC-CEUS two- dimensional mode, the image orientation was flipped to align with the anatomical position of the patient in the standing position. In three-dimensional Render mode, the system generated images comparable to CT reconstructions, clearly depicting the spatial relationships among the urethra, bladder, vagina, and VVF, thereby enhancing clinical interpretability \u003csup\u003e[\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e\u003cp\u003eThe key aspects of VVF surgery include locating the fistula, assessing its size, number, and location, and evaluating its relationship with the bilateral ureteral orifices to determine the optimal surgical approach. When the fistula is clearly visualized and the vaginal condition is favorable, low VVFs (fistula located in the bladder trigone) are typically managed via a transperineal approach. In contrast, high VVFs (fistula located above the bladder trigone), which are more likely to involve the ureters, are better suited for a transabdominal approach. In this study, IC-CEUS was first used to accurately localize the VVF site. Subsequently, pelvic floor three-dimensional ultrasound was employed to acquire volumetric images of the region of interest. Using TUI technology, three orthogonal planes (A, B, and C) were reconstructed, enabling intuitive three-dimensional visualization of the pelvic floor structures. This technique clearly displayed the tissue echoes of the bladder, VVF, and vagina, and precisely localized the bladder-side openings of the VVF. It also enabled visualization of the relative positions of the bilateral interureteric ridge and ureteral orifices, allowing classification of VVFs into high (fistula located above the ureteral ridge) and low (fistula located below the ridge in the bladder trigone). The distances between the fistula openings and the bilateral interureteric ridges were measured to provide critical information for surgical planning and risk assessment\u0026mdash;an advantage unique to this technique.\u003c/p\u003e\u003cp\u003eFurthermore, this study established a four-step standardized operating procedure (SOP) for VVF diagnosis (Fig.\u0026nbsp;1): (a) Perform left and right fan scanning using two- dimensional pelvic floor ultrasound in the mid-sagittal plane. (b) In intracavitary ultrasound mode, dynamically observe the presence or absence of a vesicovaginal fistula. (c) In harmonic mode, use three-dimensional Render mode to obtain a stereoscopic image of the VVF. (d) In fundamental mode, apply three-dimensional TUI to measure the distances between the bladder-side opening of the VVF and the bilateral ureteral orifices and the bladder neck.\u003c/p\u003e\u003cp\u003eThe results of this study confirm that IC-CEUS offers significant advantages in the diagnosis of VVF, with diagnostic accuracy markedly superior to that of traditional imaging modalities. Research on the application of IC-CEUS in VVF diagnosis remains limited. Based on our findings, IC-CEUS\u0026mdash;being noninvasive, radiation-free, and capable of real-time dynamic imaging\u0026mdash;not only enables precise localization of the fistula and assessment of its three-dimensional spatial relationships but also allows for quantitative measurement of distances between the fistula and key anatomical landmarks. These capabilities provide a robust foundation for clinical decision-making. Future research should focus on establishing standardized operating protocols, developing intelligent auxiliary diagnostic systems, and exploring surgical navigation applications. Advancements in these areas will further enhance the overall diagnosis and treatment of VVF and ultimately improve patient outcomes.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eVVF Related Parameters\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"4\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eHigh position\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eLow position\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eNumber of cases\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e/\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eFistula diameter(mm)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e10.4\u0026thinsp;\u0026plusmn;\u0026thinsp;7.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e8.7\u0026thinsp;\u0026plusmn;\u0026thinsp;4.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.58\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eDistance between VVF and left ureteral opening(mm)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e28.8\u0026thinsp;\u0026plusmn;\u0026thinsp;15.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e-8.1\u0026plusmn;-2.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.003\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eDistance between VVF and right ureteral opening(mm)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e27.1\u0026thinsp;\u0026plusmn;\u0026thinsp;14.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e-9.2\u0026plusmn;-2.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.003\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eDistance between VVF and bladder neck opening(mm)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e/\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e7.3\u0026thinsp;\u0026plusmn;\u0026thinsp;1.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e/\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003eVVF\u0026nbsp; \u0026nbsp;vesicovaginal fistula\u003c/p\u003e\n\u003cp\u003eIC-CEUS\u0026nbsp;\u0026nbsp;intracavitary contrast-enhanced ultrasound\u003c/p\u003e\n\u003cp\u003eBMI\u0026nbsp;\u0026nbsp;body mass index\u003c/p\u003e\n\u003cp\u003eTUI\u0026nbsp;\u0026nbsp;three-dimensional \u0026nbsp;tomographic \u0026nbsp; ultrasound \u0026nbsp;imaging\u003c/p\u003e\n\u003cp\u003eCTU\u0026nbsp;\u0026nbsp;computer\u0026nbsp;tomography\u0026nbsp;urography\u003c/p\u003e\n\u003cp\u003eMRU\u0026nbsp;\u0026nbsp;magnetic\u0026nbsp;resonance\u0026nbsp;urography\u003c/p\u003e\n\u003cp\u003eSOP \u0026nbsp;standardized\u0026nbsp;operating procedure\u003c/p\u003e\n\u003cp\u003eBL \u0026nbsp; \u0026nbsp; \u0026nbsp;bladder\u003c/p\u003e\n\u003cp\u003eU \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;urethra\u003c/p\u003e\n\u003cp\u003eV \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; vagina\u003c/p\u003e\n\u003cp\u003eRU \u0026nbsp; \u0026nbsp; \u0026nbsp;right ureteral orifice\u003c/p\u003e\n\u003cp\u003eLU \u0026nbsp; \u0026nbsp; \u0026nbsp;left ureteral orifice\u003c/p\u003e\n\u003cp\u003eAN \u0026nbsp; \u0026nbsp; \u0026nbsp;anterior\u003c/p\u003e\n\u003cp\u003eUP \u0026nbsp; \u0026nbsp; \u0026nbsp; superior\u003c/p\u003e\n\u003cp\u003ePO \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;posterior\u003c/p\u003e\n\u003cp\u003eDOWN \u0026nbsp;Inferior\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe \u0026nbsp; authors \u0026nbsp;would \u0026nbsp;like \u0026nbsp; to \u0026nbsp;thank \u0026nbsp;everyone \u0026nbsp; who \u0026nbsp;contributed to \u0026nbsp;our \u0026nbsp; study \u0026nbsp;especially \u0026nbsp;staff \u0026nbsp; from \u0026nbsp;the \u0026nbsp;Urology \u0026nbsp; Department, Hospital Jinhua.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eYelin Lou drafted and revised the manuscript.Tian Yang collected the data and performed the statistical analysis. Yang Hu conceived and revised this study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis work was supported by the Zhejiang Province Medical and Healthy Technology Project (2025KY1747);\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData availability\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe data that support the findings of this study are available from the cor\u003c/p\u003e\n\u003cp\u003eresponding author upon reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was approved by the the Ethics Committee of Jinhua Central Hospital (Ethics Review No 52 of 2018). Informed consent was obtained from the participants or their legal representatives.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor details\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e1Department of Ultrasonography, Affiliated Jinhua Hospital, Zhejiang University School of Medicine，Jinhua Municipal Central Hospital, Jinhua 321000, China；\u003c/p\u003e\n\u003cp\u003e2Department of Urology, Affiliated Jinhua Hospital Zhejiang University School of Medicine，Jinhua Municipal Central Hospital, Jinhua 321000, China；\u003c/p\u003e\n\u003cp\u003e3Department of Ultrasonography, Jinhua Maternal and Child Health Hospital, Jinhua 321000, China；\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eRandazzo M, Lengauer L, Rochat C-H, Ploumidis A, Kr\u0026ouml;pfl D, Rassweiler J, et al. 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Identifying Patients With Vesicovaginal Fistula at High Risk of Urinary Incontinence After Surgery. Obstet Gynecol. 2016;128:945\u0026ndash;53.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eTadesse S, Mekete D, Negese S, Belachew DZ, Namara GT. Urinary incontinence following successful closure of obstetric vesicovaginal fistula repair in Southern Ethiopia. BMC Womens Health. 2024;24:164.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eNardos R, Jacobson L, Garg B, Wall LL, Emasu A, Ruder B. Characterizing persistent urinary incontinence after successful fistula closure: the Uganda experience. Am J Obstet Gynecol. 2022;227:70.e1-70.e9.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBrowning A, Menber B. Women with obstetric fistula in Ethiopia: a 6-month follow up after surgical treatment. BJOG. 2008;115:1564\u0026ndash;9.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eGhoniem GM, Warda HA. The management of genitourinary fistula in the third millennium. Arab J Urol. 2014;12:97\u0026ndash;105.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eYan Z-P, Wang C-C, Wang Y-Y, Zhao S-T. A case with type Ⅱ vesicouterine fistula. Clin Case Rep. 2022;10:e05284.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eEl-Azab AS, Abolella HA, Farouk M. Update on vesicovaginal fistula: A systematic review. Arab J Urol. 2019;17:61\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eStrojny AA, Baran A, Wiejak K, Scholz A, Maksym RB. Diagnostic and Therapeutic Challenges of Oligosymptomatic Vesicovaginal Fistula in the Complex Case of Endometriosis. Clin Pract. 2024;14:436\u0026ndash;42.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLee D, Zimmern PE. Long-term functional outcomes following non-radiated urethrovaginal fistula repair. World J Urol. 2016;34:291\u0026ndash;6.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eYu NC, Raman SS, Patel M, Barbaric Z. Fistulas of the genitourinary tract: a radiologic review. Radiographics. 2004;24:1331\u0026ndash;52.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMacura KJ, Genadry RR, Bluemke DA. MR imaging of the female urethra and supporting ligaments in assessment of urinary incontinence: spectrum of abnormalities. Radiographics. 2006;26:1135\u0026ndash;49.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLee JK, Stein SL. Radiographic and endoscopic diagnosis and treatment of enterocutaneous fistulas. Clin Colon Rectal Surg. 2010;23:149\u0026ndash;60.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eAbou-El-Ghar ME, El-Assmy AM, Refaie HF, El-Diasty TA. Radiological diagnosis of vesicouterine fistula: role of magnetic resonance imaging. J Magn Reson Imaging. 2012;36:438\u0026ndash;42.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eYoussef A, Brunelli E, Pilu G, Dietz HP. The maternal pelvic floor and labor outcome. Am J Obstet Gynecol MFM. 2021;3:100452.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSantoro GA, Wieczorek AP, Dietz HP, Mellgren A, Sultan AH, Shobeiri SA, et al. State of the art: an integrated approach to pelvic floor ultrasonography. Ultrasound Obstet Gynecol. 2011;37:381\u0026ndash;96.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eXu E-J, Zhang M, Li K, Su Z-Z, Long Y-L, Zeng Q-J, et al. Intracavitary Contrast-Enhanced Ultrasound in the Management of Post-Surgical Gastrointestinal Fistulas. Ultrasound Med Biol. 2018;44:502\u0026ndash;7.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eFrancica G. Intracavitary contrast-enhanced ultrasound in ultrasound-guided percutaneous management of abdominal fluid collections/abscesses by a single clinician: an example of point-of-care ultrasound. J Ultrasound. 2020;23:175\u0026ndash;81.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMao R, Chen Y-J, Chen B-L, Xie X-H, He Y, Chen S-L, et al. Intra-Cavitary Contrast-Enhanced Ultrasound: A Novel Radiation-Free Method for Detecting Abscess-Associated Penetrating Disease in Crohn\u0026rsquo;s Disease. J Crohns Colitis. 2019;13:593\u0026ndash;9.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eGan L, Xie L, Li H. Trans-intrauterine contrast-enhanced ultrasound (CEUS) can be an effective approach for the diagnosis of vesicouterine fistula (VUF), especially for patients with fistulas flowing unidirectionally from the uterine cavity. Heliyon. 2023;9:e13268.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMao R, Xu E-J, Li K, Zheng R-Q. Usefulness of contrast-enhanced ultrasound in the diagnosis of biliary leakage following T-tube removal. J Clin Ultrasound. 2010;38:38\u0026ndash;40.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSun F, Cui L, Zhang L, Hao J, Gu J, Du J, et al. Intravesical contrast-enhanced ultrasound (CEUS) for the diagnosis of vesicouterine fistula (VUF): A case report. Medicine (Baltimore). 2018;97:e0478.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003ePiscaglia F, Nols\u0026oslash;e C, Dietrich CF, Cosgrove DO, Gilja OH, Bachmann Nielsen M, et al. The EFSUMB Guidelines and Recommendations on the Clinical Practice of Contrast Enhanced Ultrasound (CEUS): update 2011 on non-hepatic applications. Ultraschall Med. 2012;33:33\u0026ndash;59.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSparchez Z, Radu P, Sparchez M, Vasile T, Anton O, Tantau M. Intracavitary applications of ultrasound contrast agents in hepatogastroenterology. J Gastrointestin Liver Dis. 2013;22:349\u0026ndash;53.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"european-journal-of-medical-research","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"ejmr","sideBox":"Learn more about [European Journal of Medical Research](http://eurjmedres.biomedcentral.com)","snPcode":"40001","submissionUrl":"https://submission.nature.com/new-submission/40001/3","title":"European Journal of Medical Research","twitterHandle":"@BioMedCentral","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"BMC/SO AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Intracavitary Contrast-Enhanced Ultrasound, Pelvic Floor Ultrasound, Three-dimensional, Vesicovaginal Fistulas","lastPublishedDoi":"10.21203/rs.3.rs-7473076/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7473076/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eObjective\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eTo evaluate the diagnostic efficacy of transperineal pelvic floor ultrasound combined with intracavitary ultrasound in the assessment of vesicovaginal fistula (VVF).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods\u003c/strong\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eA total of 17 patients suspected of VVF who were referred to Jinhua Central Hospital between March 2015 and May 2025 underwent transperineal pelvic floor ultrasonography using a three-dimensional intracavitary volumetric ultrasound probe. A 1:50 dilution of SonoVue contrast agent was injected into the bladder via catheter, and the presence of fistulous communication between the bladder and vagina was dynamically observed in two-dimensional harmonic imaging mode. Three- dimensional Render mode was used to reconstruct images for visualization of the fistula’s size, number, and anatomical location. In addition, three-dimensional ultrasound tomography was employed to measure the distance between the lateral opening of the bladder and the ureteral orifice of the VVF. The ultrasound findings were subsequently compared with surgical observations.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults\u003c/strong\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eUnder intracavitary ultrasound with contrast enhancement, all 17 patients were diagnosed with VVF within 5–15 seconds of contrast injection, and all demonstrated an abnormal communication between the posterior wall of the bladder and the anterior wall of the vagina. All cases presented with a single VVF; 9 were located at the bladder neck or trigone, with a mean fistula diameter of 8.7 ± 4.9 mm. The mean distances from the VVF to the right and left ureteral openings were − 9.2 ± 2.3 mm and − 8.1 ± 2.1 mm, respectively, while the mean distance from the VVF to the bladder neck was 7.3 ± 1.7 mm. Among these, 8 cases were classified as high VVFs, with a mean fistula diameter of 10.4 ± 7.1 mm. The mean distances from the VVF to the right and left ureteral openings were 27.1 ± 14.0 mm and 28.8 ± 15.4 mm, respectively. No significant difference was observed between high and low VVFs in terms of distance from the left or right ureteral openings (P \u0026gt; 0.05). The ultrasound findings were consistent with intraoperative observations.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusion\u003c/strong\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eTransperineal pelvic floor ultrasound combined with intracavitary ultrasound provides accurate diagnosis and localization of VVF. The proposed four-step standardized ultrasound protocol demonstrates strong clinical applicability and potential for widespread adoption.\u003c/p\u003e","manuscriptTitle":"Intracavitary Contrast-Enhanced Ultrasound Combined with Pelvic FloorUltrasound: A Real-Time, Non-Invasive, Radiation-Free Method for AssessingVesicovaginal Fistulas","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-10-20 09:44:18","doi":"10.21203/rs.3.rs-7473076/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-11-25T14:58:20+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-11-03T16:42:19+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-10-25T21:14:35+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-10-24T14:13:01+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"98025594242424189802616228858224729678","date":"2025-10-20T15:41:14+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"323095803298174420745242123692056865483","date":"2025-10-18T20:09:35+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"182181409890563815687894212602251717237","date":"2025-10-11T02:52:27+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-10-07T17:45:55+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-09-08T09:41:39+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-09-02T10:24:24+00:00","index":"","fulltext":""},{"type":"submitted","content":"European Journal of Medical Research","date":"2025-08-27T15:20:28+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"european-journal-of-medical-research","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"ejmr","sideBox":"Learn more about [European Journal of Medical Research](http://eurjmedres.biomedcentral.com)","snPcode":"40001","submissionUrl":"https://submission.nature.com/new-submission/40001/3","title":"European Journal of Medical Research","twitterHandle":"@BioMedCentral","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"BMC/SO AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"d1ed09bd-8cb2-48f4-812b-d61f42817af7","owner":[],"postedDate":"October 20th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2026-01-26T16:00:30+00:00","versionOfRecord":{"articleIdentity":"rs-7473076","link":"https://doi.org/10.1186/s40001-025-03753-3","journal":{"identity":"european-journal-of-medical-research","isVorOnly":false,"title":"European Journal of Medical Research"},"publishedOn":"2026-01-19 15:57:01","publishedOnDateReadable":"January 19th, 2026"},"versionCreatedAt":"2025-10-20 09:44:18","video":"","vorDoi":"10.1186/s40001-025-03753-3","vorDoiUrl":"https://doi.org/10.1186/s40001-025-03753-3","workflowStages":[]},"version":"v1","identity":"rs-7473076","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7473076","identity":"rs-7473076","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}