If the routine urine examination reveals a plus sign for occult blood, it indicates the presence of bleeding disorders and requires further review or further ultrasound and CT examinations of the urinary system to aid in the diagnosis. The possible causes are as follows: 1. The presence of urinary tract infection, when the occult blood may appear positive, and may also appear in the urine with an elevated number of white blood cells, accompanied by urinary frequency, urinary urgency, painful urination symptoms, because the infection caused by the urinary system epithelial microscopic damage and bleeding. 2. 3. If there is a tumor in the urinary system, the tumor will destroy the epithelium of the urinary system and cause bleeding, resulting in a positive occult blood result, further auxiliary ultrasound or CT examination of the urinary system can be performed to exclude whether there is a tumor disease.