Sensitivity of the high-power field method in detecting red blood cells in the urinary sediment

The red blood cell (RBC) content of urine specimens was determined both by direct counts by a hemocytometer and by the number of RBCs per high-power field (HPF) in the sediment by routine urine analysis. The sensitivity of a finding of 1 to 3 and 2 to 4 RBCs/HPF in detecting greater than or equal to 2,000 RBCs/ml unspun urine was 63% (73/116) and 54% (63/116), respectively. There was a wide range of values of RBCs/ml determined by direct counts for each degree of microscopic hematuria as defined by the HPF method. We conclude that examination of the urinary sediment by the HPF method is not sufficiently sensitive to be used as a screening test for the detection of microhematuria in asymptomatic subjects.