Increased residual urine volume in the bladder is one of the important diagnostic tools for prostate enlargement. Due to prostate enlargement, patients have difficulty in urinating, and as the obstruction worsens, the urine in the bladder cannot be completely emptied every time the bladder urinates and remains in the bladder, which is called “residual urine”. The appearance of residual urine and its amount reflects the bladder urinary dysfunction, in the process of diagnosis and treatment of prostatic hyperplasia, the determination of residual urine is an essential step, and there are three methods of determination: transabdominal ultrasound measurement, urinary catheterization and intravenous urography. Physical examination of the bladder for increased residual urine is the patient is weak, pale, lethargic, high blood pressure, rapid pulse and deep breathing should be thought of the possibility of uremia. Abdominal examination may reveal enlarged kidneys with sphenopalatine angular tenderness, suggesting that hydronephrosis has developed secondary to hydronephrosis. The suprapubic area should be examined for a full bladder, and the surface of the bladder in urinary retention is smooth, softer, and not nodular. Patients with a long history must be noted for comorbid carcinoma, hemorrhoids, narrowing of the prepuce opening, and a normal urethra. Increased residual urine volume of the bladder other tests are as follows: 1, rectal palpation: first of all, to understand the anal sphincter muscle tone, anal canal relaxation should be thought of neurogenic bladder. Prostate enlargement, the middle groove disappears, the surface is smooth, the histology of the hyperplastic nodules due to the outer peripheral band formed by the pseudo-envelope, palpation is generally no nodular changes. The enlargement of both sides of the prostate may be asymmetric, and if the enlarged portion protrudes into the bladder, the upper border of the prostate may not be reached on rectal palpation. The texture of the prostate can be soft or hard, determined by the proportion of glandular components and fibrous smooth muscle present. If the prostate is irregularly enlarged, nodular or even hard as a stone, the possibility of prostate cancer should be thought of. Physical examination should monitor whether the reflex of bulbocavernosus muscle, lower limb movement and perception are normal, and discover the possible neuropathy. 2. Blood and urine examination: to evaluate the kidney function of the patient and exclude the possibility of urinary tract infection. Because infections in any part of the male reproductive system or urinary system may lead to urinary difficulties, some symptoms of BPH are similar to prostatitis, which can easily lead to misdiagnosis. Ultrasound: (also used in the diagnosis of prostate cancer) can monitor the size of the prostate for the patient. In addition, through a pressure-sensitive sensing device, the doctor can measure the force of urine flow when the patient urinates forcefully, and the decrease in the force of urine flow often suggests that the patient has the possibility of benign prostatic hyperplasia. 4. Nephrography: An X-ray examination of the urinary tract after intravenous injection of a contrast medium) is mainly used for the diagnosis of kidney and ureteral diseases, but it also has a certain diagnostic value for benign prostatic hyperplasia. Through pyelography, the doctor can find out whether there is any blockage or abnormal narrowing in the whole urinary tract of the patient, and urethral narrowing at the level of the prostate will highly suggest the possibility of the existence of benign prostatic hyperplasia. 5.Cystoscopy: We can directly find the narrowing or blockage in the patient’s urethra. Before cystoscopy, first we should inject a certain amount of anesthetic into the urethra through the urethral orifice, and then insert the probe equipped with a light into the patient’s urethra so that we can search for the narrowing part of the patient’s urethra through the monitor.