Encrustation is a recognized complication following the placement of ureteral stents or percutaneous nephrostomy (PCN) tubes, potentially leading to significant morbidity. While extensive research has examined the etiology of encrusted ureteral stents, the literature regarding encrusted PCNs remains limited. Factors implicated in ureteral stent encrustation include the duration of tube indwelling, urine composition, underlying medical comorbidities, and fluid intake. However, a clear delineation of risk factors for PCN encrustation is lacking. This study aimed to identify real-world patient-specific factors, including fluid intake, urine output, and patient demographics, associated with the development of PCN encrustation.

A retrospective cohort study was conducted utilizing data from patients who underwent PCN insertion between January 2022 and December 2024. Patients were categorized into two groups based on their percutaneous encrustation data each time: encrustation (n=91) and non-encrustation (n=635). All patients received PCNs of identical material and were diagnosed using standardized encrustation criteria. Data collection includes patient demographics, cause for PCN insertion, amount of fluid intake per day, overall urine output, urine output per each PCN, duration for exchange PCN and urine cultures. A binary logistic regression model was used to determine the statistically significant association between with encrusted PCN. A p-value of <0.05 was considered statistically significant.

Multivariable analysis revealed that female gender, body mass index < 18.5 kg/m², and underlying single kidney or chronic kidney disease were significantly associated with PCN encrustation. Furthermore, PCN encrustation was more likely to occur in patients with PCN insertion for urolithiasis or malignancy. While univariable analysis suggested that overall fluid intake and overall urine output > 30 ml/kg per day were protective factors, these associations were not sustained in the multivariable model. Conversely, urine output per PCN ≥ 10 ml/kg per day and a history of more than two PCN exchange episodes were identified as independent protective factors against PCN encrustation. Notably, bacteriuria, present in 20.79% (n = 151) of the cohort, was significantly associated with PCN encrustation in univariable analysis, although it demonstrated a trend towards significance in the multivariable model.

Urine output per PCN ≥ 10 ml/kg per day and a history of more than two PCN exchange episodes appears to mitigate the risk of PCN encrustation. These findings highlight the importance of patient counseling at the first visit to minimize the incidence of this complication.