Surgical management of incomplete duplex kidney with calculus and homolateral ureterovesical junction obstruction: a case report and literature review

Introduction

Congenital anomalies of the kidneys and urinary tract (CAKUT) comprise a large spectrum of congenital malformations such as conditions of the upper urinary tract [e.g., supernumerary, ectopic or fused kidney, duplex kidney, ureteropelvic junction obstruction (UPJO)], and phenotypes primarily affecting the lower urinary tract (e.g., ureterovesical junction obstruction (UVJO), vesicoureteral reflux, ureterocele, posterior urethral valves) (1,2). It is well noted that combined manifestations of CAKUT spectrum could coexist in the same person, which can make the management more challenging in one operation (3,4). An incomplete duplex kidney is a congenital anomaly referring to the confluence of the two separate ureters localized at somewhere above the ureterovesical orifice (5). It is generally an asymptomatic normal variant. However, some complications like kidney stone or urinary tract obstructions may be highly relevant to incomplete duplex kidneys, which usually need to be treated surgically (6,7). Currently, most of the literature focuses upon the treatment of duplex kidney with UPJO. However, the coexistence of duplex kidney and UVJO is rarely reported. Although less common than UPJO, persistent UVJO is as damaging to kidney function as UPJO (8,9).

Hence, we present a rare clinical case of left incomplete duplex kidney with calculus and homolateral UVJO that occurred in a female adult, and report the combined synchronous surgical management of lithotripsy by flexible ureteroscopy with holmium laser, and refitting the ureter into the bladder after resection of the affected segment. We present this article in accordance with the CARE reporting checklist (available at https://acr.amegroups.com/article/view/10.21037/acr-2025-117/rc).

Case presentation

A 34-year-old female patient presented to the department of outpatient with the chief complaints of intermittent left flank pain for the last week, and reported no other symptoms. Her medical, family, and psychosocial history was uneventful after detailed consultation. The patient was diagnosed of renal calculus and hydronephrosis on the left side by abdominal color Doppler ultrasound in a local hospital, but not treated. There was no abnormality in basic vital signs. On physical examination, the patient showed slight percussion pain in left renal area. On laboratory tests, blood routine examination, urine routine examination, renal function and other indicators were all in normal level, and the result of urine culture was negative. On radiology examination, computerized tomography (CT) and intravenous pyelogram (IVP) revealed left incomplete duplex kidney, hydroureteronephrosis. There are no two ureters, the duplication concerns the renal pelvis, it is consistent with a bifid renal pelvis, and both moieties were functional and drained independently (Figure 1). UVJO was diagnosed by flexible ureteroscopy. Meanwhile, CT scan revealed the calculus located in the lower moiety of the left incomplete duplex kidney, and the diameter of it was about 1.8 cm (Figure 2). The patient was diagnosed of left incomplete duplex kidney with calculus, hydroureteronephrosis and UVJO homolaterally. Spasmolysis, anti-inflammatory and analgesic treatment was applied on her for 3 days, and then she felt the pain was eased. To relieve the UVJO in order to mitigate hydroureteronephrosis and protect renal function, and meanwhile, to remove the calculus in the kidney, we performed the surgery in the following procedure after evaluating the risk of the surgery and general anesthesia.

Figure 1 IVP at 15 minutes (A), 60 minutes (B) respectively after injecting contrast medium. IVP revealed left incomplete duplex kidney [black arrow in (A) and (B)], hydroureteronephrosis [white arrow in (B)], and ureterovesical junction obstruction [red arrow in (B)]. IVP, intravenous pyelogram.

Figure 2 CT scan. A calculus (black arrow) located in the lower moiety of the incomplete duplex kidney was revealed by CT scan, and the diameter of it was about 1.8 cm. CT, computed tomography.

The patient was placed in the supine position and put under general anesthesia. After urethral catheterization and routine disinfection, a Gibson incision was made at the left lower abdomen. Then the left ureter was identified in the retrovesical space, bluntly dissected through ureterovesical junction until the stenosis section was confirmed, where the ureter was ligated, following a cutting-off proximal to the ligation point. Subsequently, the flexible ureteroscopy with holmium laser was cannulated through the cutting-off point, ascending into the renal pelvis along the ureteral lumen, to visualize a dark brown calculus localized at the calyx neck of calyceal diverticulum of the lower kidney. The calculus was fragmented gradually and carefully with holmium laser (2 J, 15 Hz). In order to avoid ureteral steinstrasse postoperatively, a Nitinol stone basket was applied to extract relatively large calculus fragments until complete clearance in sight was achieved. After lithotripsy, a double J stent was inserted to the collecting system with its upper end in the lower renal pelvis. Immediately, the vesicoureteral reimplantation surgery was performed in the light of Lich-Gregoir procedure. Briefly, A 3–5 cm detrusorotomy was made in the anterolateral direction until the bladder mucosal protrusion was observed uniformly, creating the new submucosal tunnel. After placing the lower end of the double J stent into the bladder, the ureter was imbedded in the new submucosal tunnel, the seromuscular layer was closed over it intermittently with a 5-0 absorbable suture, ensuring a tension-free and mucosal-to-mucosal anastomosis. Lastly, the drainage tube was indwelled, and the incision was closed layer by layer.

Postoperatively, the patient felt no discomfort such as lumbar distension or left flank pain, and was discharged on the third day after the drainage tube was removed. No complications were developed during the placement of the double J stent, which were removed one month after operation. No residual calculus was observed by urinary system ultrasonic examination, and meanwhile, the hydroureteronephrosis was significantly alleviated.

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 and its subsequent amendments. Written informed consent was obtained from the patient for publication of this case report and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

Discussion

The term CAKUT summarizes a large variety of congenital malformations including renal agenesis, structural duplication, mispositioning and defects in the ureter and bladder, among which duplex kidney and ureter account for about 1 in 125 births (10). Duplex kidney can be of two types based on the condition of the ureter: complete duplication and incomplete duplication. Compared with a normal kidney, complete duplication produces a duplex kidney with two poles that drain into two ureters, yet incomplete duplication leads to a Y-shaped ureter (11), which means, the two poles of a duplex kidney share the same ureteral orifice of the bladder. Most patients with duplex kidney show no clinical symptoms and do not require special treatment unless complicated with urinary calculus, infection, reflux, obstruction, hydroureteronephrosis and other complications. Although infrequently, comorbidity from within the CAKUT spectrum may coexist in the same case, and cause multiple manifestations (12,13).

Incidence of calculus disease in duplex system is around 3–8% (14), partly due to impaired drainage of the collecting system caused by urinary tract obstruction and recurrent infections (15,16). Although this disease can be easily diagnosed via Ultrasound, IVP, CT and other examination, it can be extremely challenging when surgical management is needed due to difficulties in access to the anomalous kidneys. To date, the surgical management of calculus in a duplex kidney combined with urinary junction obstruction is with several available options, such as extracorporeal shock wave lithotripsy (ESWL), percutaneous nephrostolithotomy (PCNL) (17), (flexible) ureteroscope lithotripsy (fURL), retroperitoneal laparoscopic ureterolithotomy, and robotic pyelolithotomy etc. There are advantages and disadvantages for each treatment. ESWL is recommended only for small stones and where urinary drainage is not hindered. If the patient has a large stone burden in an anomalous kidney, to reduce the incidence of steinstrasse, it can be debulked using PCNL followed by J stent insertion and treatment of residual calculi using ESWL. Endoscopic surgery has emerged as novel surgical approaches, gradually replacing traditional open surgery. With the introduction of flexible instruments, virtually the whole collecting system can be inspected. The fURL and holmium laser technique provides a reasonable alternative to other procedures in the management of renal calculi (18,19), and can be considered as a first option for managing selected patients before PCNL (20), to shorten the hospital stay and postoperative recovery time. Laparoscopic or robotic procedures are for complex renal stones an alternative for patients in whom open procedures are considered, not ESWL, PCNL or other endoscopic procedures (21). Robotic pyelolithotomy has emerged as a valid and increasingly adopted approach for patients with complex anatomy and large stone burden—particularly when concurrent anatomical reconstruction is required. Robotic pyelolithotomy allows for complete stone clearance under direct vision, anatomical correction in the same session (e.g., pyeloplasty or ureteral reimplantation), preservation of renal function in anatomically distorted collecting systems (22,23). In clinical practise, management of calculus in abnormal kidneys must be individualized, considering the size and site of the stone, as well as the location, function and anomaly of the kidney. “Stone dust” and “residual fragments” refer to independent entities after lithotripsy. “Stone dust” is defined in vitro by a stone particle size criteria of 250 µm, translating clinically as particles able to be fully aspirated through a 3.6-Fr working channel (WC) without blockage, while “residual fragments” relates to ≤2 mm calculus fragments on postoperative non-contrast CT following holmium laser lithotripsies (24). The reason we chose fURL for lithotripsy was that the following vesicoureteral reimplantation surgery needed a cutting-off on the ureter, and it could also be the ureteroscopic access into the ureter. UVJO is characterized by a total or partial obstruction of urine flow in the distal portion of the ureters which is one of the conditions included in the heterogeneous group of CAKUT. UVJO can be caused by a poorly peristalsing ureteral segment near the bladder, abnormal insertion of the ureter into the bladder, a short intravesical ureteral segment, infection, scar tissues, kidney stones and other factors (25,26). Although still uncertain, its pathogenesis is associated with an abnormality or delay in the development of the muscles of the distal ureteral portion during the 20th week of pregnancy (27). It should be mentioned that UVJO is considered the leading cause of prenatal hydronephrosis, defined as the dilation of the renal calyces and/or pelvis, which can lead to a progressive deterioration of kidney function and, consequently, irreversible damage to the organ (28,29). From our point of view, if an obstructed segment or anatomic ureteral anomalies are present, then resection of the affected segment and refitting the ureter into the bladder is one of the current treatment options.

In this case, we deduced that UVJO and duplicate kidney predisposed the patient to hydroureteronephrosis and calculus in the kidney. We performed vesicoureteral reimplantation to relieve ureteral end obstruction and maintain patency of the ureteral opening after reimplantation in the bladder, which has an antireflux effect and does not affect the physiological function of urinary storage and voiding of the bladder. Although the patient was content with the treatment until the submission, two limitations should be noted. That is, on account of the rarity nature of this case, more evidence should be collected comprehensively. Moreover, longer term outcomes of the patient are to be seen by expanding the follow-up time.

Conclusions

This report documents a rare case of multiple renal anomalies that included left incomplete duplex kidney with calculus, hydronephrosis, and homolateral UVJO. The related literature review gives some insights about the management of CAKUT. The results showed that a combined surgical procedure of fURL and ureterovesical reimplantation may be a safe and effective approach for this disease presentation. Hopefully, our experience can be used as reference for similar cases.

Acknowledgments

None.

Footnote

Reporting Checklist: The authors have completed the CARE reporting checklist. Available at https://acr.amegroups.com/article/view/10.21037/acr-2025-117/rc

Peer Review File: Available at https://acr.amegroups.com/article/view/10.21037/acr-2025-117/prf

Funding: This work was supported by General Project of Chongqing Natural Science Foundation (No. cstc2021jcyj-msxmX0611, to Y.S.), Chongqing Doctor “Through Train” Scientific Research Project (No. CSTBBSXM2022-JCX0007, to Y.S.), and Education and Training Reform Project of Army Medical University (No. 2022B28, to Y.S.).

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://acr.amegroups.com/article/view/10.21037/acr-2025-117/coif). Y.S. reports that this work was supported by General Project of Chongqing Natural Science Foundation (No. cstc2021jcyj-msxmX0611), Chongqing Doctor “Through Train” Scientific Research Project (No. CSTBBSXM2022-JCX0007), and Education and Training Reform Project of Army Medical University (No. 2022B28). The other 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 and its subsequent amendments. Written informed consent was obtained from the patient for publication of this case report 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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