Diagnostic value of urine erythrocyte morphology in the detection of glomerular disease in SurePath™ liquid-based cytology compared with fresh urine sediment examination

Objective: To assess whether the morphology of urine erythrocytes can be an effective tool for distinguishing glomerular disease from lower urinary tract disease in SurePath (TM) liquid-based cytology (SP-LBC). Methods: We examined four morphological parameters of erythrocytes: (1) irregular erythrocytes (of all types including fragmented forms) comprising greater than or equal to 20% of erythrocytes; (2) uniform erythrocytes (>80%); (3) doughnut or target-like shaped (D/T) erythrocytes (=1%); and (4) acanthocytes (=1%) in glomerular disease (n = 32) and lower urinary tract disease (n = 20) with SP-LBC slides in cases that had also been assessed by fresh urine sediment examination. Results: Sensitivity of D/T erythrocytes and acanthocytes (dysmorphic erythrocytes) for glomerular disease were 100% and 87.5%, respectively, with urine sediment examination, and 81.3% and 46.9%, respectively, in SP-LBC slides. Specificity was 100% for D/T erythrocytes and acanthocytes using either procedure. While irregular erythrocytes were specific for glomerular disease using urine sediment examination, they were seen in 70% of those with lower urinary tract disease using SP-LBC slides as a result of the deformation of erythrocytes by the fixative. Conclusions: Although the sensitivity of D/T erythrocytes and acanthocytes for glomerular disease was lower in SP-LBC slides than fresh urine sediment examination, their specificity was equally high. Therefore, urine erythrocyte morphology is useful in the detection of glomerular disease with the SP-LBC slides. However, morphological features apart from D/T erythrocytes and acanthocytes are not useful in SP-LBC slides.