ABSTRACT
Accurate differentiation between upper and lower urinary tract infection [UTI] requires invasive produces. The objective of this study was to determine the morphology of RBC that originates from kidney or bladder for differentiating between upper and lower urinary tract infection. UTI was induced by the injection of 0.5ml of normal saline containing human E coli [10[4]/cc] into the bladder of rats [n=50]. After 48 hours, the rat urine was drained from the bladder and analyzed for the morphology of RBC, culture and cell counter. For diagnosing pyelonephritis, both bilateral kidneys and bladder were biopsied for histopathology and culture. Dysmorphic RBC was detected in 33% [10/30] of the subjects with upper UTI and 13% [4/30] with lower UTI, which showed no significant difference [x[2] =0.04, P=0.63 Fisher Exact Test]. The mean and SD of percentage of dysmorphic RBC in the subjects with upper and lower UTI were 35 +/- 34% and 44 +/- 43%, respectively, which revealed no significant difference [t=0.55, P=0.25]. In this study, dysmorphic RBC showed rates of 45% sensitivity and 50% specificity for upper UTI diagnosis. Urine osmolality may influence the results of RBC morphology for differentiating between upper and lower UTI