Is urine occult blood and hematuria the same thing? Nowadays, most of the urinalysis tests use urine analyzers, one of which shows urinary occult blood, so is positive urinary occult blood the same as hematuria? First of all, let’s understand the principle of urine occult blood test: if there are red blood cells in the urine, there is a kind of hemoglobin in the red blood cells for ferrous hemoglobin, which has weak peroxidase activity and can make the oxide in the urine test paper (such as peroxyanisole) release new ecological oxygen, which in turn can oxidize the test paper with o-toluidine to blue. The instrument then 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 red blood cells may be present in the urine. The use of urine occult blood test to determine the presence of hematuria is mainly intended to be convenient and quick, and is suitable for outpatient screening of hematuria. If vitamin C is used clinically, it will be excreted from the urine in large amounts, and it neutralizes the oxides in the urine test paper, which cannot produce oxygen and cause a false reaction. And when the urinary tract infection, certain bacteria can produce peroxidase, causing a false positive; some crystals can also affect the occult blood measurement, causing a false positive result; some trauma or tissue infection can cause the urine to contain myoglobin will also make the urine occult blood positive. In addition, urine occult blood test is also subject to some external factors such as whether the specimen is fresh, whether the reaction time is appropriate, whether the test strips are expired or contaminated, etc., which can cause false positive or false negative results of urine occult blood test. However, whether there are really red blood cells in the urine mainly relies on the retention of urine, centrifugation to take the sediment with microscopic observation to determine. To use an analogy, just as the police investigating a bad guy, first by visual inspection, think suspicious and then to check his identity card, check his old background. Urine occult blood is equivalent to visual inspection, urine sediment examination is equivalent to the old bottom. The visual inspection may be wrongful, and the bottom may be missed due to various reasons. Therefore, the diagnosis of hematuria should not be based on urine occult blood alone, but mainly on urine sediment microscopy. Therefore, when your child has positive occult blood in urine, parents should not be in a hurry, and further examination is needed to determine whether it is hematuria.