Urethritis is a common disease referring to inflammation of the mucosa of the urethra, with a predilection for women. Clinically, it can be divided into acute and chronic, nonspecific urethritis and gonococcal urethritis, the latter two having similar clinical manifestations and must be differentiated on the basis of history and bacteriological examination. Most are caused by retrograde invasion of pathogenic bacteria into the urethra. The common causes of urethritis are as follows: 1. urethral injury: urethral mucosal abrasions caused by urethral instrumentation can destroy the urethral mucosal defenses and lead to bacterial infection; 2. foreign bodies in the urethra: foreign bodies placed from outside or stones in the urethra can lead to urethral infection after a short pause; 3. urethral obstruction: such as circumcision stenosis, urethral stenosis, urethral stricture, posterior urethral valves, urethral tumors Female hymen umbrella, urethral hymen fusion, etc., due to poor urination, urine accumulation in the urethra can be secondary to urethral infection; 4, adjacent organ inflammation: such as prostatitis, vesiculitis, vaginitis or cervicitis can spread to the urethra, this is often a stubborn foci of chronic posterior urethritis; 5, often related to sexual life: unclean sex can easily cause urethral infection.