Bladder Stone Incarceration in Posterior Urethral Valve Leading to Urinary Retention: A Case Report

Authors: Limin Huang, Fei Liu, Yanfei Wang, Yanyan Jin, Yingying Zhang, Haidong Fu, Jianhua Mao

Abstract

Introduction

Posterior urethral valve (PUV) and vesical calculus are individually among the most common causes of obstructive lower urinary symptoms in children. Intermittent urinary retention can be caused by a combination of PUVs and bladder stones. There are very few reports of an association between PUVs and bladder calculus.

Case Presentation

We present a case of intermittent urinary retention resulting from a stone obstructing the PUV. The patient experienced intermittent urinary retention for over a month. A computed tomography scan revealed a bladder stone in the posterior urethra. The intracorporeal lithotripsy for calculus with fulguration of the PUV was performed using YAG laser.

Conclusion

For any boy presenting with urinary retention, we recommend a thorough urethral assessment; the absence of significant abnormalities in the urethra on voiding cystourethrography cannot rule out the presence of relevant PUV; hence, bladder endoscopy may sometimes be required for further evaluation, to rule out vesical calculus and potential PUVs.

Introduction

Posterior urethral valves (PUVs) and bladder stones are among the most common causes of obstructive lower urinary tract symptoms in children [1–4]. There are few reports on the association between PUVs and bladder stones. PUV is a common condition [1, 5]. PUVs are congenital obstructions of the posterior urethra. As this disorder develops early in gestation, the bladder and upper urinary tract are exposed to elevated pressure throughout development, leading to far-reaching changes in bladder function and renal injury. The exact etiology of PUV is unknown, but it appears to be a multifactorial gene-mediated embryopathy [6]. During embryogenesis, the caudal end of the Wolffian duct is absorbed into the primitive cloaca at the site of the future verumontanum in the posterior urethra. In healthy males, the remnants of this process are the posterior urethral folds, called plicae colliculi. Histological studies indicate that PUV is formed at approximately 4 weeks of gestation as the Wolffian duct fuses with the developing cloaca. The patient is typically a newborn with bladder outlet obstruction, diminished urine flow, and secondary urinary tract infection [7]. Most reports estimate the incidence of PUV to be in the range of 1 in 5,000 to 1 in 8,000 live births. However, estimates have varied as widely as 1 in 2,000 and 1 in 25,000. Epidemiological studies have varied in their methodology and have generally focused on diagnostic rates rather than true incidence [5, 8, 9]. In male children, a membrane layer is attached to the distal end of the posterior urethra, leading to valve-type obstruction, which causes considerable urinary retention and promotes harmful effects on the bladder and upper urinary tract. Although rare, when the obstruction can be overcome by detrusor contraction, it may remain silent until later in life [10], eventually causing chronic kidney disease and often progressing to end-stage kidney disease [11]. Most boys with PUV are diagnosed and treated within a few days or months after birth (usually after prenatal testing), which limits the time for stone formation. However, patients with advanced PUV may have a greater chance of having stones, which may lead to the occurrence of stone-related symptoms [12]. Here, we report a case of acute urinary retention (AUR) caused by the combination of a PUV and a bladder stone.

Case Report

A 7-year-old male patient presented with a 30-day history of micturition difficulty and AUR. Over this period, he sought medical attention at multiple healthcare facilities on several occasions, where temporary relief was achieved through indwelling catheterization. However, upon catheter removal, symptoms of dysuria and urinary retention recurred. The patient’s medical history revealed no prior seeking of medical consultation for similar complaints. There was no documented history of lithuria, hematuria, or recurrent febrile episodes. General physical examination findings were unremarkable. Routine hematological investigations and urine culture results were within normal limits. Abdominal ultrasonography demonstrated bladder wall thickening with no abnormalities noted in the upper urinary tracts. During the voiding cystourethrogram (VCUG) examination, the child’s bladder appeared normal; however, the urethra could not be assessed for abnormalities because the child did not urinate during the procedure (Fig. 1). It is possible that the radiopacity of the primary component of the pediatric patient’s bladder stone is significantly lower than that of ioversol, which may explain the failure to detect the stone during VCUG. Therefore, in order to crush stones and detect the condition of the bladder and urinary tract, we chose to further perform cystoscopy (Fig. 2). The patient subsequently underwent cystopanendoscopy, which revealed PUV type I, as shown in Figure 3. An impacted calculus measuring approximately 10 mm was noted just proximal to the PUV, and it was pushed back into the bladder. Intraoperatively, the patient’s relative was informed of the presence of associated PUV, and consent was obtained for fulguration. The intracorporeal lithotripsy for the calculus with fulguration of the PUV was performed using a YAG laser. Complete stone clearance was achieved. The postoperative period was uneventful, and the patient was discharged after Foley catheter removal on postoperative day 5. The CARE Checklist has been completed by the authors for this case report, attached as online supplementary material (for all online suppl. material, see https://doi.org/10.1159/000545455).

Discussion

PUVs are congenital obstructions of the posterior urethra. As this disorder develops early in gestation, the bladder and upper urinary tract are exposed to elevated pressure throughout development, leading to far-reaching changes in bladder function and renal injury. The exact etiology of PUV is unknown, but it appears to be a multifactor gene-mediated embryopathy [6]. During embryogenesis, the most caudal end of the Wolffian duct is absorbed into the primitive cloaca at the site of the future verumontanum in the posterior urethra. In healthy males, the remnants of this process are the posterior urethral folds, called plicae colliculi. Histological studies suggest that PUV is formed at approximately 4 weeks of gestation as the Wolffian duct fuses with the developing cloaca. When the insertion of the mesonephric ducts into the cloaca is anomalous or too anterior, normal migration of the ducts is impeded, and the ducts fuse anteriorly, resulting in the formation of abnormal ridges or folds, which are believed to be the origins of 95% of PUVs; this type is referred to as type I PUV [13]. Although Young et al. [14] described type II PUV, most pediatric urologists believe that these are not obstructing valves but simply hypertrophy of the plicae colliculi. Type III valves constitute the remaining 5% and are characterized by a ring-shaped membrane located distal to the verumontanum, featuring a central perforation. The formation of these valves is attributed to incomplete dissolution of the urogenital membrane [15]. Familial inheritance is uncommon but has been documented. PUVs exhibit a range of severity. The extent of obstruction caused by this abnormality varies according to the configuration of the obstructive membrane within the urethra. The incidence of PUV is not only limited to transient urethral obstruction but also includes congenital obstruction of the urinary tract during a critical period of organogenesis, which can profoundly and permanently affect the function of the kidney, ureter, and bladder.

Inflammation and infection were the most frequent causes of AUR [16]. AUR in children is a rare condition with very heterogeneous causes. Although the majority of cases exhibit mild underlying conditions such as balanoposthitis or fecal impaction, serious reasons, such as malignant diseases, especially in the first year of life, must be excluded. PUV is a common cause of urinary tract obstruction in male neonates and children. Urethral calculus in children is a rare occurrence, and its association with PUV is even rarer, with only a handful of reported cases in the literature [1, 17]. Most boys with PUV are diagnosed and treated within a few days or months of birth, often following prenatal testing, which helps minimize the time available for stones to form. However, individuals with advanced PUV may have an increased risk of developing stones, potentially resulting in the manifestation of stone-related symptoms [12]. Bladder stones are uncommon in developed nations, particularly among children, but their prevalence increases in low- and middle-income countries due to inadequate nutrition, poor water sanitation, and warmer climates. They constitute 5% of all urinary stones. The primary risk factors for bladder stones include bladder outlet obstruction, neurogenic bladder, recurrent urinary tract infections, and the presence of foreign bodies [18]. In males, the most common location for urethral calculi is the posterior urethra, where they may become impacted at the site of a PUV. Urethral calculi can present with symptoms such as hematuria, AUR, and dysuria. These symptoms can overlap with those of PUV, making it challenging to diagnose on radiological imaging whether the symptoms are due to PUV or the calculus. Plain X-ray KUB and VCUG are necessary for evaluation, but VCUG may not conclusively determine whether the dilatation is caused by PUV or the impacted calculus [19]. Cystourethroscopy is the most definitive diagnostic and therapeutic modality for these clinical entities, whether considered individually or in combination. In adult patients, stones smaller than 7 mm can be easily retrieved without the need for lithotripsy, through a cystoscopic sheath, with or without the assistance of a stone removal system [20]. Children have a narrow urethra, which means the stone-sized threshold for lithotripsy should be kept on the lower side. A high index of suspicion is necessary when these two clinical conditions are diagnosed together. Currently, the best that modern medicine can offer for these children is close urologic care following full-term delivery, with the aim of maximizing bladder and renal function for the benefit of the child’s long-term health [21].

Conclusion

Urethral calculi can present as hematuria, AUR, and dysuria. We would like to emphasize that PUV should be suspected in pediatric patients presenting with bladder or urethral stones. These symptoms may overlap with those of PUV and can be challenging to diagnose via radiographic imaging, irrespective of whether they are caused by PUV or stones [19]. X-ray plain films, including KUB and VCUG, are required for evaluation; however, VCUG may not be able to determine whether the dilation is caused by PUV or stone impaction. Bladder and urethral endoscopy is the most definitive diagnostic and treatment method for these clinical conditions, whether used alone or in combination.

Statement of Ethics

This study was approved by the Ethics Committee of the First Affiliated Hospital of Zhejiang University School of Medicine (No. 2024GR0287), Hangzhou, China. Written informed consent was obtained from the parent/legal guardian of the patient for publication of the details of their medical case and any accompanying images. We have received written informed consent for the publication of these details and any accompanying images.

Conflict of Interest Statement

The authors have no conflicts of interest to declare.

Funding Sources

This research was supported by the Natural Science Foundation of Zhejiang Province (LTGD24H050002) and the Medicine & Health Technology Project of Zhejiang Province (2024646275).

Author Contributions

L.H., F.L., Y.W., Y.J., Y.Z., H.F., and J.M. participated in the acquisition of clinical data. L.H. wrote the manuscript and J.M. revised the manuscript. All authors have read and agreed to the published version of the manuscript.