Blood in the urine is known as hematuria, also known as blood in the urine. Under normal circumstances, there are no red blood cells in urine. Normal urine contains a very small number of red blood cells. Uncentrifuged urine can have 0 to 2 red blood cells per high magnification field under the microscope. If the eye can see that the urine is “watery” or blood-colored, or even if there is blood or blood clots in the urine, it is called carnal hematuria. It is worth pointing out that not all hematuria can be detected by the eyes. More than 95% of hematuria is due to urinary tract infections, of which glomerular diseases, kidney cysts and stones, prostate enlargement and urinary tract infections are the most common. Hematuria may also be caused by hemorrhagic cystitis, urinary stones, renal tuberculosis, renal tumors, and kidney and urethral injuries. Hematuria is one of the main symptoms of these diseases. Differential diagnosis of hematuria 1.When urination starts with hematuria and then becomes normal, it is usually caused by urinary infection and urethral disease; 2.If urination starts normally and ends with hematuria, it is mostly caused by cystitis and prostate disease; 3.If it is “whole hematuria” with dark red blood, it is usually caused by kidney disease. Common urinary diseases that cause hematuria 1, urinary stones The harm caused by urinary stones ranges from “light” to “heavy” and is often accompanied by hematuria. In mild cases, they only cause some symptoms such as distension and discomfort in the kidney area or abdomen, and the movement of stones usually causes renal colic and hematuria. In heavy cases, due to large stones, multiple stones or stones located in the urinary tract for too long, urine outflow is blocked, resulting in urinary tract infection and ureteropelvic fluid accumulation, and kidney function damage. 2, prostate hyperplasia Hematuria is a common symptom of prostate hyperplasia, mostly manifested as an increase in the number of urination, incomplete urination and shortening of the urine line, and sometimes the symptoms of hematuria. This is because the capillaries in the mucous membrane on the surface of the prostate gland become congested, dilated and twisted when the bladder contracts or the enlarged prostate pulls, these capillaries will rupture and cause hematuria. The root cause of hematuria in patients with prostatic hyperplasia is the benign lesion of the complication, and in severe cases the hematuria may also be due to a urinary tract tumor. It is worth noting that irregular treatment often causes device injuries, such as performing cystoscopy, catheterization, and bleeding caused by urethral dilation. 3.Cystitis Most of the cystitis occurs in the bladder mucosal epithelium, which grows faster and the surface is prone to break down and bleeding, so the most common symptom of cystitis is hematuria without any feeling, which can be seen by naked eyes. This is a unique “abnormal urination” sign of bladder cancer. Hematuria is most often seen throughout urination, or only at the beginning or end of urination. The hematuria is often painless and intermittent, and can be reduced or stopped on its own, which can easily create the illusion that the disease has been cured. A few patients with bladder cancer may experience increased urination, urgency and painful urination as if they have cystitis, but antibiotics are ineffective. Patients with painless hematuria or patients with long-term incurable cystitis should promptly seek medical attention and receive urine exfoliative cell examination. 4. Urinary infection Renal hematuria refers to hematuria originating from the glomerulus, which is clinically manifested as simple hematuria, or hematuria with proteinuria, and is mostly seen in patients with urinary infection. If the treatment is incomplete, recurrent or miss-treatment and mis-treatment, the condition cannot be controlled effectively and efficiently, which eventually leads to uremia. It is necessary to eliminate the causes of renal hematuria because long-term lesions of the glomerular basement membrane can also lead to glomerulosclerosis, which can cause damage to the kidneys. Therefore, renal hematuria must be treated early.