Normal human fresh urine is a light yellow transparent liquid, when the urine contains blood, it is called hematuria. If the urine contains more than 1-2 ml of blood per 1000 ml of urine, the urine is seen as red or washed water-like to the naked eye, which is called carnal hematuria. If the urine is not abnormal to the naked eye but red blood cells are found in the urine under the microscope, it is called microscopic hematuria. Hematuria is the most common symptom of urological diseases, and the first symptom of many urological diseases is hematuria, such as acute and chronic nephritis, urinary tract infection, urinary stones and urological tumors. What I would like to emphasize here is “painless hematuria”, which is characterized by the absence of other accompanying symptoms and discomfort except for one abnormality, hematuria, which can disappear temporarily without treatment, and intermittent hematuria. Whenever the hematuria disappears, the patient always thinks that the “disease” is also eliminated. In fact, this kind of intermittent and painless hematuria is often a clinical manifestation of urological tumor, and if the hematuria suddenly worsens, it is often the advanced stage of the tumor. What is the cause of “painless hematuria”? The first and foremost is bladder tumor, which accounts for almost 50% of the cases, and most of these cancers occur in middle-aged and older men over 50 years old, and in recent years, there is a trend of rejuvenation. In my clinical work, I often meet such patients. When they start to have painless hematuria, they do not realize its harmfulness and think it is “fire”, so they just take some medicine to get rid of fire, plus the hematuria disappears soon after taking the medicine, so they do not take it seriously. In the future, although you often find that your urine is light red, you don’t pay too much attention to it because you don’t have any other reactions or pain. Often, it is only when the hematuria is obviously aggravated or even found to be mixed with blood clots in urine after a few months that they panic and seek medical attention, and by then most of them are already in the middle or late stage of bladder cancer. We say that early stage bladder cancer can be cured by simple transurethral resection of bladder tumor (TURBT), but middle to late stage bladder cancer often requires radical cystectomy + bowel substitution bladder surgery, which is a severe test of patient’s physical endurance and can lead to a significant reduction in quality of life, which is really more than worth the loss! In addition, renal pelvis/ureteral tumors are an important cause of “painless hematuria”. “Painless hematuria” is an early symptom of renal pelvis and ureteral tumors. Since there is no other obvious discomfort, it is often taken lightly by patients and some doctors, mistaking it for urinary tract infection or stones, and failing to carry out systematic examination and proper treatment. When the tumor invades the nerves around the renal pelvis/ureter, the patient will feel pain in the lower back, which is usually at an advanced stage and the time for timely treatment has been lost. I have also encountered a case of misdiagnosis of renal pelvis and ureteral cancer as bladder cancer in my clinical treatment, which I remember very well now. The patient in that case was an old woman in her eighties who had repeated “painless hematuria” and blood clots in her urine for one year. After ultrasound, pelvic CT and cystoscopy, it was confirmed to be “bladder cancer”. As planned, radical cystectomy + bowel replacement cystectomy was planned. However, it was found that the ureter on one side was enlarged and stiff, and the ureteral cavity had a broad-based tumor that continued to the renal pelvis when the patient was incised, and the kidney was closely adhered to the surrounding area (considering the extensive invasion and metastasis of the tumor to the perinephron), which could not be removed. These lessons show how important it is to systematically investigate patients with “painless hematuria”! Finally, it is important to note that patients with prostate cancer and prostatic hyperplasia may also present with “painless hematuria”. This type of patient is often associated with significant urinary frequency, urgency, painful urination, difficulty urinating, and urinary retention, etc. An anal finger examination can reveal an abnormal prostate, and a blood test for prostate-specific antigen (PSA) and ultrasound of the prostate can help with the diagnosis. I recently treated a case of an old man who presented with “painless hematuria”. Various tests failed to find a urological tumor, and there was no evidence of prostate cancer, but the prostate had mild hyperplasia/hypertrophy. The diagnosis of prostatic hyperplasia must be considered only if urological tumors and prostate cancer can be adequately ruled out! In short, “painless hematuria” is an important early sign of urinary tract disease, especially bladder tumors.