Are all urgent nephrostomies that urgent?

Abstract

To investigate if the presence of systemic inflammatory response syndrome (SIRS) in patients with urinary tract obstruction at time of presentation to the emergency department correlates with a subsequent positive urine culture and to determine if it could be used as a tool to predict the urgency of a percutaneous nephrostomy (PCN). The secondary aim of the study was to assess the incidence of in-hour and after-hour emergent PCNs performed in a tertiary center which has both interventional radiological and urological expertise. Emergent adult PCN cases referred from the emergency department between 2011 and 2016 were identified retrospectively. Urine culture results, clinical features of SIRS, timing of procedure, and radiological findings were analyzed. A total of 110 patients met the inclusion criteria. There were a total of 60 male and 50 female patients with a mean age of 62 (age range 18-99years). Ninety-two (83%) PCN patients were referred and performed on after-hours with the remaining 18 patients performed in-hours. There were 53 (48%) patients that met the criteria for obstruction with SIRS and 57 (52%) patients with obstruction without SIRS. The number of after-hours PCN performed in both groups was equal at 46 patients each. The most common cause of obstruction in the SIRS group was stone related in 31 (58%) patients. Whereas, the most common cause of obstruction in the non-SIRS group was due to malignancy in 26 (45%) cases. An elevated temperature and heart rate were the most common features of SIRS at 96 and 83% respectively in the SIRS group. An organism was isolated in 35 (67%) out of the 52 urine culture results obtained for the SIRS group. No organism was isolated in 42 (95%) out of the 44 urine culture results obtained in the non-SIRS group. Statistical analysis using Fisher's test revealed that the association between obstruction without SIRS and a negative urine culture result was statistically significant (p< 0.0001). A large percentage (50%) of PCN cases performed after-hours could have been performed during daytime hours instead due to the absence of infection. This would be in line with the practices of some centers that consider an infected obstructed kidney as the only absolute indication for emergent decompression overnight. The study also demonstrates that the absence of a SIRS in a patient with urinary tract obstruction correlates well with a negative urine culture result from the nephrostomy specimen which has a high negative predictive value for excluding pyonephrosis.