Congenital ureterovaginal fistula: a rare case of single-system ectopic ureter opening into the vagina with ipsilateral ectopic kidney diagnosed via ultrasound

Introduction

An ectopic ureter (EU) is defined as a ureter opening in a location other than the trigone of the bladder. There are two causes of EU and ureterovaginal fistula (UVF): congenital and acquired abnormality (surgery, traumatic injury. inflammatory diseases, radiation therapy, etc.). Congenital EU involves no history of surgical trauma and is present from birth. The incidence of EU is estimated to be approximately 1 in 2,000 in newborns and ranges from 1 in 2,000 to 1 in 4,000 in the general population, and the male-to-female ratio is approximately 1/6–1/2 (1). In approximately 80–85% of cases, the EU is concurrent with a duplicated renal collecting system, while in the remaining 20%, a single renal collecting system is observed (2). Additionally, it has been found that female patients with EU may have concurrent genital tract anomalies (3,4). UFV is the one of malformations of EU and involves the presence of an abnormal communication channel between the ureter and vagina. The incidence of UVF is extremely low, being present in about 25% of EU cases (5).

Typically, various imaging modalities are employed in the examination of EU and UVF, including ultrasound (US), intravenous pyelography (IVP), magnetic resonance urography (MRU), computed tomography (CT), and urography. US is generally considered for the first-line evaluation of urinary tract malformations. It can show a dilated ureter along its course as well as the degree of hydronephrosis in the collecting system. However, the diagnosis of single-system EU (SSEU), especially when accompanied by a small dysplastic, poorly functioning kidney, is challenging for conventional imaging modalities. In this paper, we present a rare case of congenital UFV, in which SSEU was first diagnosed by US and further evaluated by CT urography.

Case presentation

A 13-year-old girl was admitted to The Second Affiliated Hospital of Nanchang University with a history of persistent leakage of urine from the vaginal opening, about 20 mL per day since birth; in spite of this, she had a normal voiding pattern. The girl was not menstruating and had no family history of urinary or genital malformations. The patient visited multiple hospitals and was simply misdiagnosed as having “absence of right kidney”. The family members accompanied here to the urology department of our hospital for further comprehensive examination. Clinical examination showed no obvious abnormalities of the external genitalia. US examination of the abdomen revealed the following findings: (I) compensatory enlargement of the left kidney; (II) absence of the right kidney in the right renal fossa and absence of the right ureteral orifice in the bladder triangle; (III) a double uterus, double vagina, and normal ovaries; (IV) a predominantly cystic mixed echogenic mass on the inner side of the right iliac vessels, measuring approximately 19×17 mm in size, with color doppler flow imaging (CDFI) showing a few blood flow signals in the solid portion; and (V) a sausage-shaped anechoic structure with a width of approximately 3.3 mm in front of the right side of the vagina, with its upper end appearing to converge with a cystic mixed echogenic mass on the inside of the right iliac vessels through a long hypoechoic channel and its lower end terminating at the right vagina (Figure 1A-1F). As the EU opening into vagina with ipsilateral ectopic hypoplastic kidney was highly suspected, subsequent CT urography was performed, which revealed the following: (I) a normal left kidney and ureter, (II) a hypodysplastic right kidney with malrotation of the pelvis, and (III) a portion of opacified urine flow into the vagina through a leaking right UVF as indicated by ultra-delayed (30 min) acquisition (Figure 2A,2B). Subsequently, a laparoscopic right ureteronephrectomy was performed by a urological surgeon, with kidney structures measuring approximately 43×25×15 mm in size and adjacent to the right iliac vessels being exposed intraoperatively (Figure 3). According to the postoperative pathological results of the specimen (Figure 4A-4D), and imaging and macroscopic surgical view, the patient was ultimately diagnosed with a right hypodysplastic kidney, a pelvic kidney, an ipsilateral EU opening into the vagina, a double uterus, and a double vagina. Postoperation, the patient’s urinary continence was restored completely, and follow-up was unremarkable.

Figure 1 Ultrasound images. (A) There was a normal ureteral opening (orange arrow) on the left, but no ureteral opening in the right triangle; (B) absence of right kidney in the right renal fossa; (C) a predominantly cystic-mixed echogenic mass 19×17 mm in size on the inside of the right iliac vessels, with CDFI showing a few blood flow signals in the solid portion; (D) a sausage-shaped anechoic structure located in front of the right vagina, about 3.3 mm wide; (E) a double uterus; and (F) a double vagina (yellow arrows). BL, bladder; RL, right liver; CDFI, color Doppler flow imaging.

Figure 2 CT urography. (A) A hypoplastic kidney in the right iliac fossa and ectopic opening of the ureter (white arrow). (B) Contrast medium leakage from the right ureter (red arrow) to the vagina (yellow arrow) through a fistula apparent on the delayed enhancement scan. CT, computed tomography.

Figure 3 Gross specimen of the dysplastic kidney (red arrow) and ureter (yellow arrow).

Figure 4 HE images of the atrophic and dysplastic kidneys showing some glomeruli (yellow arrow) and tubules (red arrow) at (A) 50×, (B) 100×, (C) 200× and (D) the right ureter (white arrow) at 50×. HE, hematoxylin and eosin.

All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Helsinki Declaration (as revised in 2013). Written informed consent was obtained from the patient’s legal guardians for publication of this article and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

Discussion

The majority of EUs, particularly those in females, are identified during childhood due to persistent urinary dribbling or recurrent urinary tract infection that prompt clinical evaluation. The clinical symptoms of the patient usually depend on the insertion site of the EU, which differs between males and females due to physiologic differences. Among females, the predominant locations for EU insertion include the bladder neck and upper urethra (33%); the vaginal vestibule (33%), situated between the urethra and vaginal opening; the vagina itself (25%); and less frequently, the cervix or uterus (<5%) (1,6). Most girls with ureteral drainage into the vagina, as reported (1), experience small leakage or spotting incontinence, as the insertion of the EU bypasses the exterior urinary sphincter. In males, however, hydronephrosis can frequently occur, but urinary incontinence is extremely rare due to the insertion of ureter over the external urinary sphincter.

In our case, the girl also had a malformation of the genital tract, with close relationship between the urinary and genital systems stemming from their common embryological origin and developmental processes. During early embryogenesis, both systems develop from the same embryonic structure, the intermediate mesoderm. In addition, the formation of the urinary and genital systems involves the Wolffian and Mullerian ducts. Improper development of these ducts can lead to congenital abnormalities in both the urinary and genital tracts (7). Therefore, when detecting one or more malformations of the urinary system or genital malformations, clinicians should be alert to the simultaneous presence of congenital abnormalities in both, subject patients to a more comprehensive and detailed evaluation, and combine at least two disciplines for integrated diagnosis and treatment.

It is worth mentioning that CT/magnetic resonance imaging (MRI) has unparalleled advantages, especially in evaluating whether there is a double or single collecting system and in identifying location of the ectopic opening. US can also be used as a first diagnosis in some patients in whom the EU insertion can be demonstrated and recommended due to its convenience, lack of radiation, and low cost.

The case reported here provides certain insights. (I) When no renal structure is detected in the renal fossa, renal absence should not be immediately diagnosed. The scope of the scan should be expanded, especially to scan the iliac fossa, to exclude the possibility of a pelvic ectopic kidney. (II) In patients with vaginal leakage of urine, if cystic solid structures are found next to the normal ovaries, this should suggest the possibility of dysplastic ectopic kidney. (III) The location of the bladder opening of the ureter should be closely attended to in order to rule out an ectopic opening of the ureter. (IV) When the patient develops unexplained leakage of urine, regardless of the patient’s age, an EU opening should be considered, and it is necessary to further scan the uterus and vagina, as abnormalities of the genitourinary system often occur in combination.

Acknowledgments

Funding: None.

Footnote

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://qims.amegroups.com/article/view/10.21037/qims-24-213/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Helsinki Declaration (as revised in 2013). Written informed consent was obtained from the patient’s legal guardians for publication of this article and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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