The observation of erythrocytes under a microscope can confirm that the “blood” result on your report is, in fact, due to the presence of red blood cells. A smaller number of red blood cells may be observed as compared to the reagent strip. This may be due to urine that is too diluted (see your density result) or poor storage conditions. Conversely, in rare instances, a few red blood cells can be observed even if the reagent strip was negative. In this case, it is the microscopic observation that the physician should consider.
Blood is very often present in vaginal secretions. If your analysis also shows the presence of squamous cells, specimen contamination may be responsible for some or all of the blood detected.
In the absence of contamination, the presence of more than 3 to 5 erythrocytes per field on more than one occasion may signal one of a number of kidney or urinary tract infections (bladder infection, inflammation [cystitis]; kidney stone; urinary tract tumour or cancer, etc.).
If your report indicates the presence of erythrocyte casts, this means the blood comes from the kidney itself (glomerulonephritis) rather than the ureter, bladder and urethra.