Hematuria is the presence of an abnormally high number of red blood cells in the urine. No or occasional red blood cells (0-2/HP) are seen in the urine of normal people. Red cells seen only under the microscope are called microscopic hematuria; flesh-washing or blood-colored urine that is visible to the naked eye is called carnal hematuria. Hematuria can be changed in different ways, such as transient hematuria, intermittent episodes of hematuria and persistent hematuria. Transient hematuria (only 1-2 routine urine tests with red blood cells greater than or equal to 3/HP) is usually seen after strenuous activity, high fever, cold, heavy physical labor, prolonged standing, menstruation and other physiological conditions. Intermittent episodes of hematuria and persistent hematuria are mainly seen in pathological conditions, of which 98% of hematuria is caused by diseases of the urinary system itself, suggesting abnormal bleeding in the kidney and or urinary tract, which is an alarm of possible serious diseases of the urinary system, and only 2% of hematuria is caused by systemic hemorrhagic diseases or lesions of organs adjacent to the urinary system. Etiology of hematuria: 1. Urinary system diseases (1) stones: such as kidney, ureter, bladder, urethral stones, oxalate urine, etc.; (2) infections: such as fetus specificity seen in acute pyelonephritis, cystourethritis, prostatitis. Specificity is seen in infections caused by tuberculosis, fungi, viruses. (3) nephritis: such as acute nephritis, IgA nephropathy, thylakoid proliferative nephritis, membranoproliferative nephritis, crescentic nephritis, focal proliferative nephritis, membranous nephropathy, and focal segmental glomerulosclerosis. (4) Tumors: such as kidney, ureter, bladder, urethra, prostate tumors, etc. (5) Hereditary and congenital diseases: if congenital arteriovenous fistula, congenital hoof-iron kidney, thin basement membrane nephropathy, Alport syndrome, nail-patellar syndrome, polycystic kidney, medullary sponge kidney, congenital isolated kidney, cavernous hemangioma, etc. (6) vascular diseases: malignant hypertension, renal artery embolism, renal vein thrombosis, renal arteriovenous malformation, ruptured urinary tract varicose veins, lumbago-hematuria syndrome, etc.; (7) injury: such as injury to the kidney, ureter, bladder, urethra, etc. (8) Embolism or thrombosis: such as renal infarction, renal vein thrombosis, etc. (9) Other causes: such as renal aneurysm, endometriosis in the bladder, etc. 2, systemic diseases such as hematologic diseases, immunologic diseases, infectious diseases, cardiovascular diseases, endocrine metabolic diseases, allergic poisoning, etc. 3.Urinary tract adjacent organ diseases Common inflammatory diseases and tumors: such as acute appendicitis, pelvic inflammatory disease or abscess, ureteritis or abscess, etc. 4, drugs and chemical factors such as sulfonamides, indomethacin, mannitol, cyclophosphamide, etc. 5.Functional hematuria See in healthy people, such as post-exercise hematuria and renal prolapse, etc.