When it comes to urodynamic testing, we have to start with urination, an extremely common physiological phenomenon in everyday life. You may think that urination is a simple and natural process, but that is because you are a healthy person. It is not uncommon to see children suffering from urinary disorders in daily urology practice. What is urodynamic testing and what kind of patients is it appropriate for? First we introduce the normal process of urination. When the urine produced by our kidneys accumulates to a certain volume in the bladder, the bladder expands and the bladder wall becomes tense, and the special receptors in the bladder wall transmit this tension to the urinary center of the spinal cord, which at the same time transmits this impulse to our brain, creating the urge to urinate. If it is judged by the brain that it is possible to urinate, this command reaches down to the spinal cord and through a special reflex arc causes contraction of the detrusor muscle and relaxation of the internal urethral sphincter, the posterior urethra relaxes, resistance decreases and urine is pressed into the posterior urethra. When urine enters the posterior urethra, the receptors in the urethra are stimulated and transmitted to the spinal urinary center via the pelvic nerve, which inhibits the anterior horn cells of the sacral 2 to 4 segments and relaxes the external urethral sphincter by reducing the tense efferent impulses of the pubic nerves, so urine is forced to be driven out. From the above introduction, we can learn that the complex process of urination involves the interaction of the relevant nerves and muscles. Failure of any one or several parts of the voiding process to cooperate correctly with each other due to physiological or pathological influences can result in a variety of voiding disorders. Urodynamics is a method to analyze and find the cause of urinary difficulties by monitoring and measuring the entire process of urination. Urodynamics is the application of the basic principles and methods of fluid mechanics and electrophysiology to detect urine flow rate, pressure and bioelectrical activity in various parts of the urinary tract based on the anatomical characteristics of each part of the urinary tract, so as to understand the function and mechanism of urinary tract discharge of urine. Urodynamics is a powerful tool for urologists to diagnose urologic disorders, as it can be used to understand the dynamic processes of urine storage and voiding in patients, and can be used to directly investigate the physiological conditions of patients with urologic symptoms. Urodynamic examination can obtain the length and pressure distribution of the urethral sphincter, the pressure changes in the bladder during bladder storage and voiding, the degree of coordination between the forceps and sphincter, and the rate of urine flow during voiding, and can also be used to understand the physiological process of bladder pressure exceeding urethral pressure during straining in patients with stress urinary incontinence. The test provides the clinician with a wealth of clinical information to make the most accurate diagnosis. The patient is examined with a cystometric tube and an anal tube placed through the urethra. If a neurourinary pathology is suspected, a perianal electrode may be applied to obtain the required information. If the patient is suspected of having a neurological pathology, such as spinal cord injury or spinal cord surgery, a perianal electrode may be applied to obtain all the information. Patients with the following symptoms may need to undergo urodynamic testing. Special emphasis should be placed on the diagnosis by a urologist to determine if urodynamic testing is really necessary. Difficulty urinating, dribbling, waiting for urine, nocturia; 2. Frequent urination that interferes with daily life; 3. Urgency and even leakage of urine; 4. Leakage during exercise, coughing or heavy lifting; 5. Poor urination after spinal or pelvic surgery; 6. Incontinence combined with memory loss and mobility problems; 7. Inability to urinate or control urine after brain hemorrhage, cerebral infarction or traumatic brain injury; 8. including: trauma, tumor and congenital malformation.