Occult blood in urine (+) refers to blood in urine. Clinically, the causes of blood in urine include infections, urinary stones, tumors, congenital malformations, trauma and internal diseases, as follows: 1. Infections: acute bacterial cystitis, acute pyelonephritis and other infectious diseases; 2. Urinary stones: especially when acute ureteral stones obstruct, blood in urine is likely to occur to varying degrees; 3. Commonly, there are metastatic cell carcinomas of the renal pelvis, ureter and bladder; 4, congenital malformations of the urinary tract: mostly seen in congenital malformations such as nutcracker syndrome, stenosis of the renal pelvis and ureteral junction, posterior ureter of the vena cava, horseshoe kidney and duplicate kidney; 5, trauma to the urinary tract: mostly seen in different degrees of kidney injury and bladder injury, post-exercise hematuria is mainly seen in young adults, appearing after exercise, relieved after rest and completely normal. 6, internal diseases: such as blood diseases, coagulation mechanism disorders, patients taking anticoagulant drugs for a long time, can also appear with blood in the urine.