Formation and composition of crust in the nephrostomy tube of patients undergoing percutaneous nephrostomy

To investigate the formation and composition of crust in the nephrostomy tube (NT) of patients undergoing percutaneous nephrostomy (PCN). Consecutive patients undergoing PCN for the treatment of obstructive nephropathy who then underwent NT exchange between January 2020 and May 2022 were included in the study. The composition of crust in NTs was analyzed using infrared spectrum automatic analysis system. A total of 46 NTs were collected from 46 consecutive patients (19 men, 27 women; mean age, 68.5 ± 13.4 years) who underwent PCN. The median indwelling time of NTs was 96 days (Q1, 90 days; Q3, 140 days). Among the 46 NTs, 20 (43.5%) were positive for the presence of crust. The mean indwelling time was significantly longer in NTs positive for crust than in those negative for crust (169.7 ± 55.7 days vs 86.5 ± 15.0 days; P < .01). In the NTs positive for crust, the crust was composed of mixed components (apatite carbonate and magnesium ammonium phosphate hexahydrate, n = 7; apatite carbonate and calcium oxalate monohydrate, n = 4) in 11 NTs and a single component (apatite carbonate, n = 5; anhydrous uric acid, n = 2; calcium oxalate monohydrate, n = 2) in 9 NTs. When the NT indwelling time was longer than 3 months, the incidence of crust formation in the NT was significantly increased. Crust was most commonly composed of mixed components. In light of these findings, we suggest that NTs should be exchanged every 3 to 4 months to prevent the formation of crust and thus prevent obstruction of the NT.