Vaginitis is the medical term for inflammation or infection of the vagina (birth canal). It typically occurs when there is a decrease in the acidity (increase in pH level) of the vagina or an infection. In premenopausal women, the normal pH level of the vagina is approximately 4.0 on the 0 to 14 pH scale that goes from acid to alkaline. This acidity normally limits the development of infectious bacteria, fungi and parasites. Vaginitis may also result from reduced levels of estrogen  that occur after menopause.

The glands inside the vagina and cervix (the bottom part of the uterus) produce small amounts of fluid. The fluid is discharged from the vagina daily, carrying out old cells that have been shed from the vaginal lining. This is the body’s way of ensuring that the vagina remains clean and healthy.

Vaginal discharge is typically clear or milky in appearance and odorless. The color and consistency of the discharge may change during menstruation and become thicker during ovulation, breastfeeding and sexual arousal. Other changes in the discharge, such as a difference in color or odor, often indicate that a woman has vaginitis or a sexually transmitted disease (STD).

There are several types of vaginitis. The three most common types are:

• Bacterial vaginosis (BV). Caused by an overgrowth of one of several organisms (bacteria) that are usually present in the vagina.
  
  
• Yeast infection (genital candidiasis). Caused by an overabundance of Candida, a microscopic fungus that normally inhabits the vagina.
  
  
• Trichomoniasis. Caused by a parasite in the vagina, typically the Trichomonas vaginalis.

It is possible for women to experience multiple types of vaginitis at the same time. Therefore, a diagnosis of BV does not necessarily preclude a diagnosis of yeast infection.

Vaginitis does not typically cause serious complications in patients. However, some types have been associated with pelvic inflammatory disease (PID) and an increased risk of STDs, including the human immunodeficiency virus (HIV). In addition, some types of vaginitis may pose certain risks for pregnant women, such as premature delivery and low birth weight babies (weighing less than 5 pounds, 8 ounces, or 2,500 grams at birth).