Hematuria, commonly known as “blood in the urine” or “blood in the urine”, refers to the presence of red blood cells in the urine, which makes the urine red in color, and can be classified according to the degree of severity into: visual hematuria (red urine visible to the naked eye) and microscopic hematuria (red urine not visible to the naked eye but indicated by several + in the urine test). This is not visible to the naked eye, but a urine test indicates the presence of several + red blood cells). Under normal circumstances 0-3 red blood cells can be present in the urine under a high magnification microscope, and when it exceeds this, it becomes microscopic hematuria, and when it can be seen with the naked eye, it becomes carnal hematuria. There are many causes of hematuria, and every organ of the urinary system can bleed: kidneys, ureters, bladder, prostate, urethra, etc. And the most common causes are: infections, stones, tumors, trauma, etc. Infection: It means that there is inflammation, and some inflammation is due to inflammation of the kidneys, caused by poor filtration and reabsorption of the kidneys due to inflammation of the kidneys, and this part of the patients is best treated through nephrology consultation. In the clinical setting, a hematuria localization test can be performed to distinguish where the bleeding is. In other patients, if there is a previous history of tuberculosis, it is important to note whether the hematuria is caused by renal tuberculosis. If it is inflammation of the bladder, there are usually also symptoms such as frequent urination, urgency and painful urination at the same time. Stones: urinary stones can usually be diagnosed by x-ray or ultrasound. However, it is not true that all patients who have stones will have hematuria, it is just one possible cause of hematuria. Usually, stones in the ureter are more likely to cause bleeding in the urinary system. Tumors: Patients over the age of 40 who develop hematuria in the naked eye must be alert to the possibility of tumors. Urological tumors (pyel cancer, ureteral cancer, bladder cancer, or kidney cancer invading the renal pelvis) can cause hematuria, and it is a painless hematuria of the naked eye. Of these, bladder tumors have the highest incidence and are one of the most common causes of hematuria. Therefore, it is important for patients with painless carnal hematuria to be seen to find out the cause behind the hematuria. Other diseases of the urinary system, such as prostate cancer or inflammation, polycystic kidney, etc., may also complicate bleeding, and patients who have their own hematologic disorders, such as poor blood clotting and capillary disease, may also cause bleeding. Of course, we also have to pay attention to whether or not we have been taking some drugs that can easily cause bleeding recently, such as aspirin and phenolic drugs. In addition, if the patient has a history of pelvic radiotherapy or has had chemotherapy for bladder irrigation, it can also lead to radiotherapy cystitis, and hematuria can occur.