Uncommon Complication: SUB Device Migrates Into Ureter and Bladder in a Papillon

Case Report: Long-term complications of subcutaneous ureteral bypass migration in an adult female Papillon

Boram Lee, Jeonghyun Seo, Soon-Wuk Jeong

Background
Subcutaneous ureteral bypass (SUB) devices are a widely used alternative to traditional surgery for relieving ureteral obstructions in veterinary patients, with lower mortality and complication rates. However, long-term complications are increasingly being recognized. This case report presents the first documented instance of a SUB catheter migrating into both the ureter and bladder in a dog, with complications monitored over nearly three years.

Methods
A 6-year-old spayed female Papillon with a solitary left kidney and ureterolithiasis underwent fluoroscopy-guided placement of a SUB device. Postoperative management included regular imaging, serum chemistry, urine culture, and ultrasound-guided flushing of the SUB system. Clinical follow-up extended to 1,072 days. Catheter positioning, kidney function, and urinary tract infections were closely monitored throughout.

Results
Initial SUB placement normalized renal parameters and improved hydronephrosis. However, inflammation was noted around the nephrostomy catheter by day 212, progressing to migration through the renal parenchyma into the ureter by day 901. The cystostomy catheter migrated into the bladder lumen by day 796. The SUB shunting port also extruded, necessitating surgical removal of the system (except for the nephrostomy catheter) by day 930. Despite these complications, renal function remained stable, and ureteroliths resolved spontaneously by day 1063.

Limitations
The nephrostomy catheter was not removed during the revision surgery due to owner preference, posing a potential risk for future complications. The case is a single-subject report, limiting generalizability. Furthermore, the absence of histopathological confirmation restricts definitive conclusions about the mechanisms underlying catheter migration.

Conclusions
This case highlights the potential for delayed and progressive migration of SUB components into adjacent structures, including the ureter and bladder. Inflammatory responses, possibly triggered by the Dacron cuff and infection-associated biofilms, are likely contributors. Regular, long-term monitoring is essential for early detection and management of complications. Surgical removal of the device should be considered when migration, obstruction, or infection arises.

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