One of the results of the urine analyzer test is urine occult blood, so is a positive urine occult blood means hematuria? The principle of the urine occult blood test is that the test paper reacts with oxidizing agents in the urine by oxidation. If there are red blood cells in the urine, the red blood cells dissolve and release hemoglobin, which is a kind of ferrous hemoglobin with weak peroxidase activity, causing the test paper to start an oxidation reaction, releasing neo-ecological oxygen, which in turn can oxidize the o-toluidine carried in the test paper to blue. The urine analyzer determines whether or not the urine is positive for occult blood or the degree of positivity based on the shade of this coloring, and thus presumes that there may be red blood cells in the urine. Note: At this time, if there are other substances of oxidant nature in the urine can also appear positive for urine occult blood, such as urinary tract infection, certain bacteria can produce peroxidase; some crystals in the urine can also affect the determination of occult blood, resulting in false positive results; some trauma or tissue infection can make the urine contain myoglobin will also make urine occult blood positive, etc. Therefore, whether there are really red blood cells in the urine mainly relies on the retention of urine, centrifugation to take the sediment and microscopic observation to determine. Therefore, the clinical significance of positive urine occult blood is to check whether there is an increase in red blood cells in the urine, if there is only an isolated positive urine occult blood in the urine routine, there is no diagnostic significance.