Renal Ultrasound Correlates with Renal Nuclear Scan in Upper Tract Surveillance of Spinal Cord-Injured Patients

Purpose: Renal ultrasound (RUS), renal nuclear scan (RNS), and intravenous pyelogram (IVP) are the most common studies used for surveillance of upper urinary tracts of spinal cord-injured (SCI) patients with neurogenic bladder (NGB). There is lack of consensus regarding which upper urinary tract studies should be incorporated in the routine surveillance protocol of SCI/NGB patients. We sought to determine if it is necessary to include both RUS and RNS as part of routine upper tract surveillance in SCI patients. Materials and Method: We retrospectively reviewed the medical records, including RUS and RNS reports, of 178 SCI patients treated at the Miami VA Medical Center during the years 1996-2001. The mean age was 56 years (range, 22-84 years). Of these 178 patients, 162 had a total of 478 paired and matched RUS and RNS studies (i.e., one RUS and one RNS, generally scheduled within 48 hours of each other) suitable for analysis. 16 patients were omitted from the study because they lacked paired and matched studies. The RUS and RNS studies were interpreted separately by different radiologists, and the findings were subjected to statistical analysis to find correlation between them, using Goodman and Kruskal's gamma coefficient. Results: Patients' levels of injury included cervical (74), thoracic (76), lumbar (21); in 7 patients, the level of SCI was unrecorded. Management of the patients consisted of spontaneous voiding with or without Crede (91), clean intermittent catheterization (42), sphincterotomy (30), and indwelling catheter (40), either suprapubic or Foley. In 361 paired and matched studies, both RUS and RNS were normal. In 56 paired and matched studies, both were positive for an upper tract abnormality. In 42 other paired and matched studies, the RUS was negative and the RNS was positive. In the final 19 paired and matched studies, the RUS was positive and the RNS was negative. The gamma coefficient between RUS and RNS was 0.924 (p < .005). Conclusion: Upper urinary tract surveillance of SCI patients can be performed solely with RUS, which is noninvasive, widely available, and less costly than RNS. Additionally, RUS provides anatomic information about the upper tracts not shown on RNS. By incorporating yearly RUS study of SCI patients, further upper tract imaging can be reserved for those cases in which the RUS reveals positive findings.