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Combined three-dimensional multiplanar and tomographic ultrasound imaging for the diagnosis and preoperative planning of female urethral diverticulum: A prospective studyYelinLou1✉Phone+86-13735688911Emailsnowflack100@163.com
YangHu2
TianYang3
1Department of Ultrasound, affiliated Jinhua hospitalJinhua Municipal Central Hospital, Zhejiang University School of Medicine321000JinhuaChina
2Department of Urology, affiliated Jinhua hospitalJinhua Municipal Central Hospital, Zhejiang University School of Medicine321000JinhuaChina
3Department of UltrasonographyJinhua Maternal and Child Health Hospital321000JinhuaChina
Yelin Lou1*, Yang Hu2,Tian Yang 3
1Department of Ultrasound, Jinhua Municipal Central Hospital, affiliated Jinhua hospital, Zhejiang University School of Medicine, Jinhua 321000, China
2Department of Urology, Jinhua Municipal Central Hospital, affiliated Jinhua hospital, Zhejiang University School of Medicine, Jinhua 321000, China
3Department of Ultrasonography, Jinhua Maternal and Child Health Hospital, Jinhua 321000, China
*Corresponding author: Yelin Lou, Department of Ultrasound, Jinhua Municipal Central Hospital, affiliated Jinhua hospital, Zhejiang University School of Medicine, Jinhua 321000, China; Tel: +86-13735688911; E-mail: snowflack100@163.com
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Abstract
Purpose
To explore the diagnostic value of three-dimensional multiplanar imaging and tomographic ultrasound imaging (TUI) in detecting female urethral diverticula.
Methods
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This study was conducted at a tertiary teaching hospital, enrolling women who underwent two-dimensional (2D) and three-dimensional (3D) pelvic floor ultrasound (PFUS) from January 2021 to January 2025. The imaging data from 3D multiplane and tomographic ultrasound were reconstructed using 4D View software. Subsequently, the ultrasonographic findings were analyzed and compared with the surgical results to evaluate their diagnostic accuracy.Results
A total of 2185 patients underwent pelvic floor ultrasound (PFUS); of these, 25 were identified with peri-urethral cystic lesions. Nineteen of these patients were suspected to have urethral diverticula, and seventeen were subsequently confirmed through transvaginal urethral diverticulectomy or soft cystoscopy.
Conclusion
Combined 3D multiplanar and TUI is a highly accurate, non-invasive, and cost-effective modality for diagnosing female urethral diverticula. It provides detailed morphological and spatial information crucial for differential diagnosis and preoperative planning.
Combined 3D multiplanar and TUI is a highly effective tool for the accurate diagnosis and precise localization of female urethral diverticula.
The visualization of the "cleft sign" at the neck of the diverticulum is a key diagnostic feature that differentiates UD from other periurethral cysts.
This non-invasive, real-time imaging approach provides crucial information for preoperative surgical planning, potentially reducing operative time and complications.
It represents a reliable and cost-effective first-line imaging modality for evaluating suspected female urethral diverticula.
Keywords:
pelvic floor ultrasound
multiplane imaging
tomographic ultrasound imaging
urethral diverticulum
diagnostic accuracy
Abbreviations TUI tomographic ultrasound imaging; PFUS Pelvic floor Ultrasound; UD urethral diverticulum
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Introduction Female urethral diverticulum (UD) is a relatively rare periurethral lesion characterized by recurrent urethral infections, nonspecific urinary incontinence, vaginal mass, or the classic "3D symptoms" (end of urinary dribbling, dysuria, and difficulty in having sex) [1]. The primary treatment for UD is surgical resection [2]. Due to its often-atypical clinical symptoms, UD has a high rate of misdiagnosis and underdiagnosis, leading to delays in diagnosis and treatment [3]. Differentiating UD from other cystic lesions in the perineal area, such as paraurethral cysts and vaginal wall cysts, is challenging. Traditionally, the diagnosis of UD relied on clinical examination or conventional imaging techniques such as ultrasound with trans-abdominal probes and MRI, which can lack clarity and be cost-prohibitive [4, 5]. Therefore, there is a critical need for a non-invasive, accurate, and accessible imaging modality for the diagnosis and preoperative planning of UD. In this prospective study, we aimed to evaluate the diagnostic value of combined 3D multiplanar and TUI in detecting and characterizing female urethral diverticula, with a focus on its ability to provide detailed morphological and spatial information for surgical guidance.
Materials and methods
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Patients This study was conducted at a tertiary teaching hospital, enrolling women who underwent 2D and 3D Pelvic floor Ultrasound (PFUS) from January 2021 to January 2025. During this period, a total of 2185 women were referred for various reasons including urinary incontinence, overactive bladder, and bladder neck obstructions. Each participant underwent a standardized interview. A
The study protocol was reviewed and approved by the Medical Ethics Committee, and informed consent was obtained from all patients.Pelvic floor ultrasound The Voluson E10 ultrasound diagnostic instrument (GE Healthcare, Milwaukee, WI, USA) was employed, equipped with a RIC5-9-D transcavitary 3D volumetric probe. This probe has a frequency range of 5–9 MHz, a 2D sweeping angle of the probe of 180°, and a 3D swing angle of 85°. Prior to the examination, patients were instructed to empty their bowels and moderately fill their bladder. They then assumed the lithotomy position. The probe, covered with a condom for hygiene, was placed snugly between the external urethral orifice and the external vaginal orifice on the patient's perineum. The initial imaging plane was the pelvic floor median sagittal section, where the probe was pressed appropriately against the perineum to ensure close contact and clear visualization of the pubic symphysis, the entire length of the urethra, periurethral tissues, and the bladder. From this plane, a 2D sweep is covered the area of interest, which included the full length of the urethra and periurethral tissues. Subsequently, an automated volumetric sweep was performed to obtain 3D ultrasound images.
Observation indicators During the ultrasound examination, observe the number, shape, and size of the UD, as well as the presence of intracapsular echoes and calcified foci, which appear as strong spots. Utilize 4D-View software for post-processing analysis and TUI to display the short-axis plane of the urethra. Set the layer spacing to 1–3 mm based on the size of the UD and select the optimal section for a complete display of the UD. Additionally, check for any urethral sphincter defects at the image junctions of various layers with the urethra and record the orientation of the UD opening. In the three-dimensional axial plane, with the urethra centered, note the orientation of the UD opening relative to a clock face. Employing multiplanar imaging technology, position the A-plane as a median sagittal section that clearly displays the entire urethra. Define the UD opening as the point of interest, precisely position it in the B and C planes, and record the relative distances from the opening to the inner and outer urethral orifices in the A-plane. In this study, UD were classified based on their structural characteristics. A single, round-like cystic structure connected to the urethra was defined as a simple UD. Conversely, a UD featuring a ring-like appearance or presenting internal segregation and calcification was categorized as a complex UD.
Statistical analysis Statistical analyses in this study were conducted using SPSS version 25.0 for Windows (IBM Corporation, Armonk, NY, USA). Continuous variables were summarized as means and standard deviations and were analyzed using the two-sample t-test. Categorical variables were reported as counts and percentages and assessed using the chi-square test or Fisher’s exact test, depending on the data distribution. A p-value of less than 0.05 was considered statistically significant.
Result Seventeen female UD patients were confirmed in the Department of Urology of our hospital from January 2021 to January 2025. There were twelve complex UD and five simple UD. The patients aged 50.08 ± 7.12 years; BMI 22.19 ± 1.9 kg/m²; and preoperative duration of disease 15.42 ± 10.28 months in complex UD. The patients aged 60.6 ± 11.01 years; BMI 23.88 ± 1.76 kg/m²; and preoperative duration of disease 9.6 ± 8.26 months in simple UD. There was no significant difference between the two groups (P > 0.05). There were 15 cases with clinical symptomatic manifestations, including recurrent urinary tract infections in 5 cases, urinary incontinence in 6 cases, postvoiding dribbling in 5 cases, and dysuria in 1 case. 15 cases had palpable cystic masses on the anterior vaginal wall, and 13 cases had fluid overflow from the external urethral orifice when the masses were squeezed. All patients underwent cystoscopy or UD resection to confirm the diagnosis.
Two-dimensional ultrasound indicators In this study, 17 cases of urethral diverticula were observed, each with clear borders. The diameter of the diverticula is 3.62 ± 0.94 mm in complex UD and 1.62 ± 0.63 mm in simple UD. Complex urethral diverticulum wall thickness of 2 mm was found in 1 person (8%), 3 mm in 4 persons (33%), 4 mm in 5 persons (42%) and 5 mm in 2 persons (17%). Simple urethral diverticulum wall thickness of 2 mm was found in 4 persons (80%), 3 mm in 1 person (20%). 5 persons in 1 cystic cavity (42%) and 7 persons in 2 cystic cavities (58%) in complex urethral diverticula. 5 persons in 1 cystic cavity (100%) in simple urethral diverticula. Of the complex diverticula, 7 were without calcification (58%) and 5 with calcification (42%). Of the simple diverticula, 4 were without calcification (80%) and 1 with calcification (20%). The echoes of the diverticula varied, with 7 hypoechoic (58%), 4 isoechoic (33%), and 1 hyperechoic (8%) in complex diverticula and 3 hypoechoic (60%), 1 isoechoic (20%), and 1 hyperechoic (20%) in simple diverticula. All 17 cases were confirmed to be free of solid tumors. Calcification and echogenicity in complex versus simple diverticula were not significantly different between the two groups (P > 0.05). Diverticulum diameter, diverticulum wall thickness and number of diverticulum chambers differed between the two groups (P < 0.05) (Table 1).
Indicator | Complex (n = 12) | Simple (n = 5) | p |
|---|---|---|---|
Age (year) | 50.08 ± 7.12 | 60.6 ± 11.01 | 0.101 |
BMI (kg/m2) | 22.19 ± 1.9 | 23.88 ± 1.76 | 0.116 |
Duration of disease (years) | 15.42 ± 10.28 | 9.6 ± 8.26 | 0.25 |
Three-dimensional ultrasound indicators The normal urethra is positioned posterior to the pubic symphysis, anterior to the vagina, and inferior to the bladder. It appears as a longitudinal, slightly curved hypoechoic band on ultrasound, exhibiting a high-to-low-to-no echo pattern from the outer to inner layers. The inner orifice connects to the bladder triangle, while the outer orifice is located at the level of the hymenal rim. In 3D TUI mode, a "cleft sign" indicative of an internal urethral sphincter defect was observed in all 17 patients at the neck of the UD (Fig. 2A, 2B). Of the complex diverticula, the urethral "cleft sign" was in the proximal urethra in 3 cases (25%) and in the mid-urethra in 9 cases (75%). Of the simple diverticula, the urethral "cleft sign" was in the mid-urethra in 2 cases (40%) and in the distal urethra in 3 cases (60%). The distance from the neck of the urethral diverticulum to the external urethral opening is 18.17 ± 3.49mm in complex UD and 26.8 ± 4.87 in simple UD, as measured on the A-plane using 3D TUI (Fig. 2E). In complex diverticula, the urethral "cleft sign" in 4 patients in the anterior urethral wall (33%) and 8 in the posterior urethral wall (67%). In simple diverticula, the urethral "cleft sign" in 5 in the posterior urethral wall (100%). In complex UD, the configuration is circumferential in 6 (50%), horseshoe-like in 5 (42%) and round is 1 (8%). In simple UD, the configuration is oval in 2 (40%) and horseshoe-like in 3 (60%). The direction of "cleft sign" in complex versus simple diverticula were not significantly different between the two groups (P > 0.05). The distance of "cleft sign", the location of "cleft sign" and the configuration of UD differed between the two groups (P < 0.05) (Table 2).
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Fig. 1
Flowchart of patient selection and diagnostic pathway for urethral diverticulum. A total of 2,185 patients underwent 2D and 3D pelvic floor ultrasound evaluation. Among them, 25 peri-urethral cystic lesions were identified. Six cases were diagnosed as paraurethral cysts based on imaging characteristics and clinical features, while the remaining 19 were classified as suspected urethral diverticula. Of these, 17 cases were confirmed as true urethral diverticula through a combination of three-dimensional multiplanar and tomographic ultrasound imaging, supported by clinical correlation. Subsequent management included transvaginal urethral diverticulectomy in 16 patients and soft cystoscopy in one case. This flowchart illustrates the diagnostic accuracy and clinical utility of three-dimensional multiplane and tomographic ultrasound imaging techniques in differentiating urethral diverticula from other peri-urethral cystic lesions.
Fig. 2
(A, B) Preoperative tomographic ultrasound imaging demonstrating the "cleft sign" of the urethra at the 4 o'clock position; (C, D) postoperative tomographic ultrasound showing resolution of the urethral diverticulum; (E) three-dimensional multiplanar ultrasound displaying the sagittal plane with measurement of the distance from the neck of the urethral diverticulum to the external urethral meatus.
Parameter | complex (n = 12) | simple (n = 5) | p |
|---|---|---|---|
Diameter(mm) | 3.62 ± 0.94 | 1.62 ± 0.63 | < 0.001 |
Thickness(mm) | 0.034 | ||
2 | 1 (8) | 4 (80) | |
3 | 4 (33) | 1 (20) | |
4 | 5 (42) | 0 (0) | |
5 | 2 (17) | 0 (0) | |
Number | 0.044 | ||
1 | 5 (42) | 5 (100) | |
2 | 7 (58) | 0 (0) | |
Calcification | 0.6 | ||
No | 7 (58) | 4 (80) | |
yes | 5 (42) | 1 (20) | |
Echogenicity, n (%) | 1 | ||
Hypoechoic | 7 (58) | 3 (60) | |
Isoechoic | 4 (33) | 1 (20) | |
Hyperechoic | 1 (8) | 1 (20) | |
Location | 0.029 | ||
Proximal urethra | 3 (25) | 0 (0) | |
Mid-urethra | 9 (75) | 2 (40) | |
Distal urethra | 0 (0) | 3 (60) | |
Distance(mm) | 18.17 ± 3.49 | 26.8 ± 4.87 | 0.012 |
Direction | 0.261 | ||
Anterior urethral wall | 4 (33) | 0 (0) | |
Posterior urethral wall | 8 (67) | 5 (100) | |
Configuration | 0.001 | ||
Circumferential | 6 (50) | 0 (0) | |
Horseshoe-like | 5 (42) | 0 (0) | |
Oval | 0 (0) | 2 (40) | |
Round | 1 (8) | 3 (60) |
Surgical and Pathologic Findings 17 patients were confirmed to have female urethral diverticula. 16 patients underwent transvaginal urethral diverticulectomy, where preoperative ultrasound localization facilitated an accurately placed inverted U-shape incision. This allowed for quick identification and access to the diverticular opening. Subsequent suture repair and reinforcement ensured that the operations were completed successfully without postoperative complications such as incisional infections or urinary fistulas. One patient underwent soft cystoscopy, which confirmed that the intraoperative position, opening, size, shape, and internal structure of the diverticulum aligned with the preoperative 3D ultrasound performance. Postoperative pathology was varied among patients, predominantly featuring migrating epithelium or squamous epithelial coverage, underlain by fibrous connective tissue and associated with chronic inflammation. Both intraoperative findings and postoperative pathology collectively confirmed the diagnosis of UD.
Discussion
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Our study demonstrates that combined 3D multiplanar and TUI is a powerful, non-invasive tool for the accurate diagnosis and precise localization of female urethral diverticula. By providing detailed morphological and spatial information, this technique facilitates differential diagnosis from other periurethral cysts and is invaluable for preoperative surgical planning.The Role of Advanced Ultrasound Techniques in UD Diagnosis UD is a cystic mass within the periurethral fascia that communicates with the urethral lumen. Its prevalence ranges from 0.6% to 6.0%, primarily affecting women aged 30 to 60 years [6]. While classification into congenital and acquired types exists, the latter is more common and is thought to arise from recurrent infections causing parafollicular cyst rupture into the urethra [7]. Identifying the communication point (the opening) is paramount for a definitive diagnosis. Current diagnostic modalities include voiding cystourethrography, MRI, and urethroscopy [8]. Voiding cystourethrography is invasive and involves radiation exposure. MRI offers excellent soft-tissue contrast but is costly and less accessible. Urethroscopy visualizes the mucosal surface but cannot assess periurethral structures. In contrast, high-frequency transperineal ultrasound is painless, provides real-time dynamic imaging, is cost-effective, and is suitable for all patients, including those with acute infections or contrast allergies [9, 10]. Our use of a high-frequency intracavitary 3D probe allowed exquisite delineation of the urethral layers and surrounding anatomy.
The Significance of the "Cleft Sign" The "cleft sign," visualized in the axial plane using TUI, represents a focal defect or thinning in the internal urethral sphincter at the site of the diverticulum's neck. This sign was present in all 17 confirmed cases in our series and serves as a direct indicator of the communication between the cystic cavity and the urethral lumen. This finding is crucial for differentiating UD from isolated paraurethral cysts, which do not communicate with the urethra and therefore lack this sign. Our results corroborate previous studies highlighting the diagnostic value of this feature [12].
Comparison with Other Imaging Modalities While MRI remains a gold standard for complex cases, our findings suggest that combined 3D ultrasound can achieve comparable diagnostic accuracy for typical presentations. Its advantages of real-time imaging, lower cost, and wider availability make it an ideal first-line screening tool. The ability to perform the examination dynamically (e.g., during Valsalva maneuver) further enhances its diagnostic yield.
Clinical Implications for Surgical Planning Precise preoperative localization of the diverticulum's opening is critical for successful surgical excision. Intraoperative urethroscopy can sometimes fail to identify small openings obscured by mucosal folds. Our technique, by accurately mapping the opening's location, depth, and relationship to anatomical landmarks (using clock-face orientation and distance measurements), enables surgeons to plan a targeted approach, minimizing dissection and potential complications. This likely contributed to the absence of postoperative complications in our surgical cohort.
Study Limitations and Future Directions This study has several limitations. First, it was conducted at a single tertiary center, which may limit the generalizability of our findings. Second, the sample size, particularly for simple UD, was relatively small, potentially affecting the power of some statistical comparisons. Third, while surgical confirmation served as the reference standard, we did not perform a head-to-head comparison with MRI or voiding cystourethrography, which are also considered gold standards in certain scenarios. Finally, the interpretation of ultrasound images is operator-dependent, and the expertise of the sonographer may influence the results. Future multicenter studies with larger cohorts and direct comparative analyses are warranted to validate our findings.
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Acknowledgement
The authors are grateful to the patients for participating in this study.
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Author Contribution
Yelin Lou: Project development, Data analysis; Yang Tian: Manuscript editing; Yang Hu: Data management, Data analysis.
Declarations
Conflict of interest The authors received no financial or otherwise support from the manufacturer of the equipment and software used in this study. The authors declare no competing interests. Funding This work was supported by funding from the Zhejiang Science and Technology Plan Project (LSY19H180006), the Zhejiang Province Medical and Healthy Technology Projects (2025KY1747) and Jinhua Central Hospital Young and Mid-Career Researcher Startup Fund (JY2024-2-06).
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