Tissues from the uterus that are sloughed off during menstruation exit the body through the birth canal. Conditions that affect the birth canal Trichomonas , candidiasis , and gonorrhea are the three most common infections of the birth canal. They are caused respectively by a protist, a fungus, and a bacterium. Vaginitis is the general name for any irritation of the vagina caused by infection or, rarely, by foreign materials that have gained entrance to the birth canal. Warts spread by sexual intercourse can sometime affect the lower part of the birth canal.
Cancer can affect the upper portion of the birth canal, especially the cervix.
Although cancer of the cervix, a common cancer in women over 50, can spread and be fatal, it also can be completely cured if detected early. A Pap smear ought to be taken at least once every three years, or annually in women over the age of 50. All sexually transmitted diseases , including AIDS , enter a woman's body most often through the birth canal. Syphilis may begin with a localized infection of the birth canal and, if not treated, spread to other organs of the body.