Trichomonas vaginitis is a common vaginitis caused by Trichomonas vaginalis. Trichomonas is pear-shaped, with a pointed rear end, and is about 2 to 3 times the size of a multinuclear leukocyte. There are 4 flagella at the top of the body, a fluctuating membrane on the body, and a protruding shaft at the rear end. The living Trichomonas is transparent and colorless, in the shape of a water drop, and the flagella swing with the fluctuation of the fluctuating membrane. The life history of Trichomonas is simple, with only trophozoites but no cyst stage. The trophozoites have strong vitality and can survive for 2 days at 3 to 5°C; 20 to 60 minutes at 46°C; about 10 hours in a semi-dry environment; and 45 to 120 minutes in ordinary soapy water. It does not grow in an environment below Ph5 or above 7.5. The vaginal pH value of patients with Trichomonas vaginitis is generally 5.1 to 5.4. Trichomonas hidden in the glands and vaginal folds often reproduce before and after menstruation, causing inflammation. It can consume or engulf the glycogen in the vaginal epithelial cells and hinder the production of lactic acid. Trichomonas not only parasitizes in the vagina. It also often invades the urethra or paraurethral glands, and even the bladder, renal pelvis, and the foreskin folds, urethra, or prostate of men. Other common vaginitis include: nonspecific vaginitis, bacterial vaginitis, candidal vaginitis, fungal vaginitis, pinworm vaginitis, allergic vaginitis, tuberculous vaginitis, vaginal Haemophilus vaginitis, amoebic vaginitis, senile vaginitis, and infantile vaginitis.