Many people often have the habit of holding urine in their lives, and some people will feel back pain after holding urine for a long time, which is actually a manifestation of distension and pain in the kidney area. Then let’s discuss the pain in the kidney area caused by holding urine. First of all, let us understand the anatomical structure and respective functions of the urinary system: the urinary system from top to bottom is roughly composed of the kidneys, ureters, bladder and urethra. The original urine is filtered by the kidneys to form urine, which first enters the pelvic ureter through secretion and is discharged into the bladder through peristalsis of the pelvic ureter. Urine is stored in the bladder, and when the urine in the bladder reaches a certain amount, it causes a voiding reflex, the bladder forceps contract and the urethral sphincter relaxes, and urine is discharged out of the body through the urethra. The first thing is that holding urine is the brain’s autonomy to control the bladder forceps contraction, so that urine in the bladder continues to accumulate, and can not be discharged in a timely manner. This phenomenon is clinically referred to as urinary reflux. When hydronephrosis reaches a certain level, it will cause pain and swelling in the kidney area, and patients often complain of back pain. A simple and effective way to prevent this disease is to urinate in a timely manner and not to hold urine. If the pain in the kidney area after holding urine is caused by lower urinary tract obstruction, it is recommended to go to the urology department to place a catheter to drain urine to reduce hydronephrosis and relieve pain in the kidney area in a timely manner.