Microscopic RBC is the abbreviation for microscopic red blood cells, which means that the number of red blood cells can be examined in the urine to see if there is an increase in the number of red blood cells. If there is an increase in the number of RBCs, it indicates the presence of a bleeding lesion. Further examination is needed to clarify the source of the bleeding, such as whether there is a urinary tract infection that causes local mucosal congestion and bleeding, or whether there is a urinary tract stone that causes local mucosal damage, resulting in an increase in the number of RBCs in the urine. The number of red blood cells in the urine may also increase due to the presence of tumors in the urinary tract that cause damage to the local mucosa and increased bleeding. Therefore, if there is an increase in the number of erythrocytes in urine, further examination is needed. It is also necessary to exclude factors of nephrogenic origin, such as glomerulonephritis and acute glomerulonephritis, which can lead to an increase in the number of erythrocytes in urine.