Features of encrustation of ureteral stents in patients with calcium oxalate and urinary acid stones

Introduction. Stent encrustation is one of the most difficult problems that can lead to difficulties in stent removal, while ureteral obstruction can lead to renal failure. Despite the search for various preventive measures, it still remains unresolved.

Aim. To study the effect of Blemaren on stent encrustation in patients with calcium-containing and uric acid stones after ureteroscopy with lithotripsy.

Materials and methods. A total of 60 patients with ureteral stones who underwent ureteroscopy with lithotripsy in A.V. Vishnevsky National Medical Research Center of Surgery from January to August 2022, were included in the study. In all cases ureteral stents 6 Ch were placed at the end of the procedure. Patients with uric acid and calcium oxalate stones (n=48) were randomized into two groups: in the main group (n=20), they were prescribed Blemaren up to the stent removal. In the control group (n=28), patients did not receive additional therapy. To determine the severity of incrustation, we used our own classification, where the percentage of lithogenic deposits relative to the lumen of the stent was calculated. Visual assessment and microscopic examination of the removed stents were performed on days 30±4.1 and 60±7.3.

Results. In patients of both groups, the severity of encrustation on the 30th day after stent placement was low (up to 30%). There were no significant differences between the groups (p=0.421). The main changes were detected 60 days after stent placement. Microscopic study revealed significant differences between two groups. In patients who did not receive Blemaren, microscopic signs of encrustation of the proximal curl of the stent occurred 2.5 times more often than in the main group (p=0.001).

Conclusions.

1. The number of encrusted stents in patients with calcium oxalate and uric acid stones who did not receive Blemaren significantly increases after two months.
2. Upper urinary tract drainage with a stent for a period of more than 2 months is possible if clinically necessary, however, preventive measures to reduce the risk of encrustation should be applied.