The vagina is a muscular canal that is visible when the labia minora are spread open. From the time of birth, a membrane of tissue called the hymen covers the opening of the vagina; this membrane is usually torn with first sexual intercourse, though it can be torn before. The vagina is usually only 3-4 in. in length, but it can expand during childbirth and slightly during sexual intercourse in women who are past the age of puberty. There are normally bacteria in the vagina, the most common type being Lactobacillus. Some common infections of the vagina (which will be discussed in detail later in the book) are fungal (yeast) infections, bacterial vaginosis, and trichomonas infections. The vagina should not hurt or itch normally. A clear, odorless discharge from the vagina is normal for some women, especially during ovulation (the production of an egg from the ovaries), which occurs in the middle of the menstrual cycle. The cells of the vagina are shed constantly. This process, and the vaginal secretions that are normally produced, keep the vagina clean. Douching is not necessary.
Women whose mothers took the medication diethylstilbestrol (DES) during pregnancy in the 1960s have a higher risk for an unusual cancer of the vagina called vaginal adenocarcinoma. It is important to tell your health care provider if you fall into this category, since special tests must be done during your yearly Pap smear to screen for this type of cancer.