Urinary red cell morphology to detect site of hematuria

We studied the urinary RBC morphology in 87 consecutive cases of significant hematuria by 3 commonly used methods: (a) light microscopy of the unstained urinary sediment; (b) phase contrast microscopy of the unstained urinary sediment; and (c) Wright's staining of the urinary sediment, in order to compare the sensitivity of these methods in detecting dysmorphic RBCs and thus predicting the site of hematuria. The clinical data and the relevant investigations were made available after the morphology of RBCs in the urine was identified. Out of the 87 patients, 45 had a glomerular and 42 had a nonglomerular cause o hematuria. Phase contrast microscopy showed a sensitivity of 91.1%, Wright's stain of 82.2% and light microscopy of 66.7% in detecting a glomerular source of hematuria. Nonglomerular hematuria could be detected in 92.9% cases by each of the 3 methods. It is concluded that phase contrast microscopy is most sensitive for the detection of dysmorphic RBCs in the urine, Wright's stain nearly as sensitive whilst light microscopy of the unstained sediment is least sensitive. Urinary RBC morphology is a useful adjunct in the diagnosis of hematuria and saves the patients from unnecessary investigations.