In normal people, there are usually no red blood cells in the urine or very small amounts of red blood cells are occasionally present. If there is an abnormal increase in red blood cells in the urine, that is, if there is more than the normal amount of blood in the urine, this is called hematuria. If the urine appears to be blood-like or washboard-like to the naked eye, this is called hematuria to the naked eye. During routine urine examination, if there are more than or equal to 3 red blood cells in a high magnification field under the microscope and cannot be detected by the naked eye, it is called microscopic hematuria. Hematuria can be caused by urological tumors, tuberculosis, inflammation, stones and other diseases, so it is important to pay attention to hematuria. If the hematuria is accompanied by symptoms such as pain, it is called painless hematuria. And painless hematuria is often an early sign of urinary tumor. Kidney cancer, bladder cancer, ureteral cancer and prostate cancer all have painless hematuria as their initial manifestation, especially bladder cancer and kidney cancer are the most common. The main symptom of bladder cancer is intermittent painless hematuria, i.e. hematuria is sometimes absent, sometimes more and sometimes less, and it can last for several days or not appear for a long time. Patients often mistakenly believe that the disease has been cured. The color of hematuria often varies depending on the amount of bleeding, acidity and alkalinity of urine, etc. It can be dark red, light red or microscopic hematuria; it can be bright red, dark red, wash water-like, often accompanied by irregular small blood clots. Due to the size, location and infection of the tumor, painful urination and difficulty in urination may also occur, and anemia and emaciation may occur in the late stage. Cystoscopy can detect early bladder tumor. Kidney tumor in early stage may have painless full course meatus hematuria, which is intermittent or persistent. The hematuria often comes on suddenly, but there are no obvious external factors. Only when the tumor invades the nerves of the perinephric tissues, there are symptoms such as back pain, and the tumor is often advanced at that time. The reason why painless carnal hematuria is so dangerous is that patients with this type of hematuria do not have any symptoms and the hematuria can often disappear on its own without treatment, so patients are often confused by its illusion and delay the diagnosis. In fact, these illusions are exactly the danger signs of urological tumors, and when the hematuria worsens, the tumor is often already at an advanced stage. There are two misunderstandings here. Firstly, not all hematuria caused by urological tumors is painless, it can also be accompanied by lumbar and abdominal pain and irritating symptoms such as urinary frequency, urinary urgency and pain; secondly, some patients think that painless visual hematuria indicates serious illness and must be treated urgently, but they are indifferent to painless microscopic hematuria. This kind of awareness is quite dangerous. The severity of urological tumor is not proportional to the severity of hematuria, which can be either painless visual hematuria or painless microscopic hematuria. In conclusion, painless hematuria is an important early sign of urinary tract tumor, especially bladder tumor, and middle-aged and elderly people especially should not ignore it. Once painless hematuria is found for the first time, you should go to hospital for examination and confirmation in order to cure the disease in the bud. Of course, various laboratory tests, X-rays, ultrasound, CT, MRI and other examinations should be performed to finally clarify what kind of disease is causing the hematuria. Currently, the incidence of urological tumors is on the increase, while hematuria as an important signal is often overlooked. Some people take the less obvious hematuria as a fire, so that the treatment is delayed. What’s more, since some hematuria can only be detected under a microscope, regular urine examination becomes an important means of prevention and treatment.