Pyuria: its relationship to bacteriuria in spinal cord injured patients on intermittent catheterization

Observations made during a study of intermittently catheterized spinal cord injured patients suggested that leukocyte counts yield higher results in aliquots of terminal-catheter urine (TCU) than in midstream-catheter urine (MCU) or suprapubic aspirate (SPA). The purpose of this study was to confirm that observation, to examine the relationship of leukocyte counts in TCU, MCU, and SPA to the leukocyte excretion rate (LER), and of pyuria to bacteriuria in this population. We collected sets of urine specimens obtained by SPA and intermittent catheterization (for leukocyte counts and quantitative culture) and timed urine collections (for LER determination). Fifty-two patients were studied for an average of five days. Leukocyte counts were performed in 241 SPA, 250 MCU, and 236 TCU specimens, and LER in 131 timed collections. The mean of the logarithm of leukocyte counts differed significantly between TCU and both MCU and SPA (p less than .0001). The difference between TCU and MCU was greater than 150 leukocytes/mm3 for 25% of paired specimens (mean 624 leukocytes/mm3, median 15 leukocytes/mm3). The statistical correlation between LER and leukocyte counts in all catheter specimens was significant; however, SPA and MCU frequently underestimated LER and TCU overestimated LER. Estimates of pyuria do not clearly separate bacteriuric from abacteriuric specimens. In spinal cord injured patients on intermittent catheterization, aliquots of catheter urine are not suitable for estimation of pyuria, and estimation of pyuria is not a feasible screening test for bacteriuria.