Presentation
Remote history of left ureteric stent insertion for ureteral calculi, now presenting with left flank pain.
Patient Data
Extensive encrustations encase the proximal and distal tips of the double J stent as well as the shaft in the proximal ureter. Bone windows better delineate the stent within the encrustations. The side holes of the stent are blocked by the encrustations, hence the dilatation of the left ureter and pelvocalyces. There is left perinephric and periureteral fat stranding and ureteral wall thickening, indicative of associated inflammation. There are also small calculi in the left kidney.
Images done under fluoroscopy demonstrate the extensive encrustations in the urinary bladder, proximal ureter, and left kidney.
Case Discussion
Encrustation refers to the deposition of mineral crystals on the stent and within the stent lumen. These can obstruct the flow of urine in the lumen or in the side holes of the stent. The stents also tend to become more fragile when encrusted, which increases the risk for stent fracture.
Encrustations preferentially develop at the tips of the stent, which may be due to ureteral peristalsis preventing deposition at the shaft.
Risk factors include increased indwelling stent times, urinary infections (from bacterial biofilm formation), dehydration, chronic renal failure, and history of lithogenic urine (stone formers). To mitigate these, patients are advised to increase oral fluid intake, get prompt treatment for urinary tract infections, and adhere to close monitoring. Regular stent replacement is the most effective method for prevention.
Monitoring is often done with either radiography or ultrasonography.
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