Men with an enlarged prostate and men and women who experience chronic urinary issues may be asked to undergo urodynamic testing, which is a method of evaluating how well the bladder and urethra are functioning in terms of urine storage and release capabilities. Patients report for urodynamic testing with a partially full bladder. They will then urinate into a special device that measures the volume and speed at which the urine is released. Any urine that remains in the bladder is drained via a catheter that is then used to fill the bladder with water or saline solution so as to evaluate how the bladder muscle responds to this pressure. External bladder pressure is also measured via a second, very small catheter that is inserted into either the rectum or vagina. Patients are asked to describe the feelings within their bladder as it is filling up. They can then re-empty their bladder with the tubes in place in what is known as a Voiding Pressure Study. X-rays are sometimes taken as the above procedures are taking place. In the several hours following urodynamic testing, patients may feel some slight discomfort when urinating and are advised to drink water every two hours to lessen this feeling.