Recently, some parents have been asking about occult blood in urine. Here I focus on answering what is going on with urine occult blood, and is it equivalent to hematuria? If urine contains a high number of red blood cells, it is called hematuria. In normal people, there are no red blood cells in the urine, or occasionally there are traces of red blood cells (0 to 2 per high-powered field of view). Transient traces of red blood cells may appear in the urine after strenuous exercise, heavy physical labor, prolonged standing and fever, and this is normal. However, if more red blood cells appear in the urine on a regular basis, this is indicative of an abnormality and should be examined closely. To examine hematuria, doctors need to collect the patient’s urine (preferably early in the morning), centrifuge it to get urine sediment, then observe whether there are red blood cells in the sediment under a microscope and count them, usually 5 per high-powered field of view will reach +, 10 will reach ++, 15 will reach +++, 20 will reach ++++, and if there are more than 50, it means sarcoid hematuria. Therefore, in some large hospitals, urine microscopy is included in the urine routine, which can be divided into microscopic red blood cells and microscopic white blood cells, and the results are expressed in terms of how many +, the more + means the heavier the hematuria or leukocyturia, and urine microscopy can truly reflect whether there is hematuria and the degree of hematuria. However, the above process is done manually by doctors, which is labor-intensive and does not cost much, so now many hospitals have eliminated urine microscopy as an item in their urine routine, and instead use machines to check urine occult blood, and use the degree of urine occult blood to indirectly reflect the degree of urine microscopy red blood cells. In fact, urine occult blood is a machine that uses a test paper to check the hemoglobin and myoglobin in the urine, and the result is between – and 4+. Most of the hemoglobin in urine comes from urine red blood cells, so there is a correlation between the degree of urine occult blood and the degree of urine microscopic red blood cells, but in the presence of myoglobin can affect the results of urine occult blood, and urine occult blood is also affected by vitamin C in urine, a large intake of fruits and fresh vegetables, vitamin C will appear in urine, which can make urine occult blood become positive or the degree of positivity increased. Therefore, urine occult blood is subject to more interference and the results are less stable. It is often seen clinically that urine occult blood is 3+ to 4+, but urine red blood cell microscopy is only + or negative. Therefore, if you find more urine occult blood, it is better to do urine microscopy and urine red blood cell count to see if there are really red blood cells and their degree.