What happens if scar tissue and fibrosis form at the ureterovesical junction (UVJ) due to chronic kidney stones?

Consequences of Scar Tissue and Fibrosis at the Ureterovesical Junction Due to Chronic Kidney Stones

Scar tissue and fibrosis at the ureterovesical junction (UVJ) due to chronic kidney stones can lead to urinary obstruction, recurrent urinary tract infections, and potential renal damage including hydronephrosis and eventual renal scarring.

Pathophysiology of UVJ Fibrosis

• Kidney stones frequently lodge at anatomical narrowings in the ureter, with the UVJ being one of the most common sites (46.3% of cases in one study) 1
• Chronic irritation from stones at the UVJ can lead to inflammation, scarring, and eventual fibrosis of the ureter 2
• The development of fibrosis represents a failed wound-healing process after sustained injury to the ureter, characterized by excessive extracellular matrix deposition 3
• Fibrotic changes at the UVJ can cause functional obstruction even after the stone has passed or been removed 4

Clinical Consequences

Urinary Obstruction

• Fibrosis and scarring at the UVJ can cause narrowing of the ureteral lumen, leading to partial or complete obstruction of urine flow 4
• Obstruction can result in hydroureteronephrosis (dilation of the ureter and kidney collecting system) 4
• Bilateral hydroureteronephrosis represents a urologic emergency requiring immediate intervention to prevent sepsis and kidney damage 4

Infection Risk

• Obstruction from UVJ fibrosis increases the risk of urinary tract infections (UTIs) 5
• Stasis of urine proximal to the obstruction creates an environment favorable for bacterial growth 4
• Recurrent UTIs may occur, potentially requiring long-term antibiotic prophylaxis 4

Renal Damage

• Persistent obstruction from UVJ fibrosis can lead to renal cortical abnormalities and scarring 5
• Renal scarring is associated with potential long-term complications including hypertension, growth impairment, and renal insufficiency 5
• The combination of obstruction and infection significantly increases the risk of renal damage 5

Diagnostic Considerations

• Ultrasonography is recommended to assess the upper urinary tract for hydronephrosis and renal scarring 5
• DMSA renal imaging may be considered to assess renal scarring and function, particularly when there is concern for significant renal damage 5
• Non-contrast CT scan provides the highest sensitivity for detecting stones and evaluating the degree of obstruction 4

Management Implications

Acute Management

• In cases of sepsis or obstructed kidney with infection, urgent decompression of the collecting system is required via either percutaneous nephrostomy or ureteral stenting 4
• Urine should be collected for culture before and after decompression to guide antibiotic therapy 4

Definitive Management

• Endoscopic management may include ureteral dilation, incision of strictures, or placement of ureteral stents 6
• Perforations during endoscopic procedures are more common in fibrotic ureters (up to 14% of cases) 6
• Use of a safety guide wire is recommended during endoscopic procedures to facilitate rapid reaccess to the collecting system in case of complications 6

Long-term Monitoring

• Regular ultrasonography is recommended every 12 months to monitor renal growth and any parenchymal scarring 5
• DMSA imaging may be considered for follow-up to detect new renal scarring, especially after febrile UTIs 5
• Serum creatinine should be monitored to assess renal function, particularly if bilateral renal cortical abnormalities are present 5

Prevention Strategies

• Early and effective treatment of kidney stones to prevent chronic irritation and subsequent fibrosis 7
• Prompt management of UTIs to prevent additional inflammation and scarring 5
• Metabolic evaluation and medical therapy to prevent recurrent stone formation 7
• Adequate hydration to reduce stone recurrence and maintain good urine flow 7

Special Considerations

• The risk of renal scarring is higher in patients with higher grades of vesicoureteral reflux (grades III-V), which may coexist with or develop secondary to UVJ fibrosis 5
• Children with UVJ fibrosis may be at higher risk for long-term renal complications and require more vigilant monitoring 5
• Patients with bilateral UVJ fibrosis are at particularly high risk for renal insufficiency and require aggressive management 4