The normal CT of occult blood in urine is mainly considered to be related to urinary system infection, nephritis, urethral trauma, and so on. 1. Urinary system infections: such as urethritis, cystitis, etc., may lead to edema, congestion, or even hemorrhage of the mucosa of the urethra and bladder, which in turn may lead to occult blood in urine. Due to the mildness of the lesion, CT may not be able to detect it. 2. Nephritis: it can also lead to slight bleeding in the affected area, triggering occult blood in urine. In some mild cases, it may not be detected by CT. 3. Urethral trauma: slight injury to the urethra may also lead to urethral capillary rupture, which may also trigger occult blood in urine, CT normal. There are many other reasons for the normal CT of occult blood in urine, such as coagulation dysfunction, etc. In this case, it is recommended that the patient seek medical attention as soon as possible for a more detailed examination to diagnose the cause of the disease and treat the symptoms.