Unprecedented Association: Bilateral UPJ obstruction with grade 3 hydronephrosis caused by Type 2 circumcaval right ureter and left lower pole crossing vessels

Abstract

Bilateral ureteropelvic junction obstruction resulting from distinct vascular anomalies on each side, with a pre-ureteric vena cava on the right and crossing vessels on the left, has not been previously documented in the literature. Even more intriguing is the association between a grade 3 hydronephrosis and a type 2 circumcaval ureter. This unprecedented report discusses this association and its management.

1 Introduction

Ureteropelvic junction (UPJ) obstruction is a common urological disorder, occurring in 1 in 1000–1500 live births, although its incidence in adults is not well-defined. Patients can present at any age, typically with flank pain, though it may also be detected incidentally. ^,

UPJ obstruction encompasses various obstructive processes, classified as intrinsic or extrinsic. Intrinsic causes include stenotic or aperistaltic segments within the ureter, while extrinsic causes, such as an accessory lower-pole renal artery, compress the UPJ externally. The role of crossing vessels in causing obstruction remains controversial.

Bilateral ureteropelvic junction obstruction is a rare and complex condition often associated with significant morbidity.

A retrocaval ureter is a rare congenital condition where the ureter is abnormally positioned posterior to the inferior vena cava (IVC). This anomaly arises from the development of the inferior vena cava rather than the urinary system. ^, Accessory renal arteries, representing persistent mesonephric arteries, are common and arise from the aorta. Numerous cases in the literature have reported that aberrant or accessory vessels often enter the lower pole of the kidney, positioning themselves in a way that obstructs urine outflow at the UPJ .

Vascular abnormalities of different origin and nature as concomitant causes of UPJ obstruction have not been previously described. This case report presents a unique instance of bilateral UPJ obstruction caused by two distinct vascular anomalies: a type 2 pre-ureteric vena cava with grade 3 hydronephrosis on the right and crossing vessels on the left.

2 Case presentation

A 21-year-old female with a history of retroviral disease, treated since birth and virally suppressed, also has a history of congenital renal conditions or anomalies of which she was unable to recall details due to her young age at the time of diagnosis and was subsequently lost to follow-up.

Presented in 2022 to the Urology department with bilateral flank pain. Laboratory tests indicated mild renal dysfunction with urea levels at 7.2 and creatinine at 107. A renal ultrasound revealed bilateral hydronephrosis assessed as moderate on the right and mild to moderate on the left. A CT Urogram performed demonstrated a right retrocaval ureter classified as a Type 2 with proximal hydronephroureterosis ( Fig. 1 a–f), accessory left renal artery and vein supplying and draining the lower pole, respectively, with these vessels crossing the proximal left ureter, likely causing obstruction of the left kidney. Additionally, a retro aortic left renal vein was noted.

Subsequently, a cystoscopy and bilateral retrograde pyelogram were performed, revealing bilateral proximal ureteric narrowing with moderate hydronephrosis. Bilateral JJ stents were placed. 6 months later, renal function improved and hydronephrosis resolved therefore stents were removed under local anaesthesia. A MAG-3 renogram conducted a year later , due to a long waiting list and limited imaging modalities and facilities, showed that both kidneys had suboptimal function, with slow drainage on the left and minimal drainage on the right. The differential function was nearly equal between the kidneys, with the left at 50.2 % and the right at 49.8 %.

In early 2024, due to increasing symptoms and worsening renal function, another retrograde pyelogram and bilateral JJ stent insertion were performed, with plans for an explorative laparotomy and bilateral pyeloplasty. Six months later, an explorative laparotomy and bilateral pyeloplasty were carried out through a midline transperitoneal abdominal incision. On the right side, dissection of the ascending colon was performed. The inferior vena cava (IVC) and the ureter were identified ( Fig. 2 ). The ureter was dissected and cut at the UPJ before being placed anterior to the IVC, followed by a simple pyeloplasty (Heineke), which was performed with a double-J (DJ) stent in place ( Fig. 3 ). On the left side, the descending colon was dissected, and the ureter was identified. The crossing vessels were then identified ( Fig. 4 ), and the stenotic segment was resected. A reanastomosis was performed with a DJ stent using the Anderson-Hynes technique. The patient had an uneventful hospital stay and was discharged home with a transurethral catheter, with both drains removed. Her urine output, renal function and septic markers were normal at discharge and remained within normal ranges on subsequent follow-up, with no symptoms reported.