Vaginal discharge is one of the most common reasons for gynaecological visits. In the US alone, it accounts for about 10 million office visits per year. 
Normal vaginal discharge in a reproductive-aged woman, also called physiological leucorrhoea, usually consists of 1 to 4 mL per 24 hours. It is typically transparent, mucousy, and white-to-yellowish. It is typically odourless but can also be slightly malodorous. The character of physiological discharge can vary over time. For instance, it becomes more noticeable with higher oestrogen states (e.g., during pregnancy, or when using oestrogen-progestin contraceptives, or at ovulation). Lactobacilli in the normal vaginal flora maintain normal acidity in vaginal discharge by producing hydrogen peroxide and lactic acid. The normal pH of leucorrhoea in reproductive women (4.0 to 4.5) creates a hostile environment for pathogens to grow. In premenarchal and postmenopausal women with low oestrogen states, vaginal pH may be 4.7 or more.
The true prevalence of this condition is uncertain because vaginitis, which encompasses the symptom vaginal discharge, is often asymptomatic, self-diagnosed, and self-treated. A telephone survey revealed that 8% of white women and 18% of black women had at least 1 episode of vaginal symptoms in the previous year. 
Professor of Clinical Obstetrics and Gynecology
Clinician Educator Track
VGL declares that she has no competing interests.
Dr Veronica Gomez-Lobo would like to gratefully acknowledge Dr Isabelle Guichard, a previous contributor to this monograph. IG declares that she has no competing interests.
Department of Obstetrics and Gynecology
Virginia Commonwealth University
DC declares that he has no competing interests.
Consultant in Sexual and Reproductive Health
Lewisham Primary Care Trust
Waldron Health Centre
LB was a member of the group that produced the 2006 Faculty of Sexual and Reproductive Health guidance on the management of women with vaginal discharge presenting in non-GU setting.
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