With so many women wondering if their vaginal discharge is normal, it seemed time to review the basics of “vaginal ecology”. We’ll be examining the following questions:
- What is normal?
- How often does it change?
- Do hormones make a difference?
- What about douching or washing?
- Does my choice of birth control have an impact?
What is “normal” vaginal discharge?
A normal discharge is made up from exfoliated vaginal skin cells, bacteria, and secretions from the cervix and vaginal walls. While as many as 30 types of bacteria can be found in normal vaginal discharge, about 95% of a healthy vaginal bacteria population consists of lactobacilli. There are several subtypes of lactobacilli, but the most important type produces hydrogen peroxide. Just like hydrogen peroxide is used to clean cuts and scrapes on the surface of external skin, the hydrogen peroxide produced by the lactobacilli helps decrease the numbers of undesirable bacteria such as E. coli, a common bowel bacteria responsible for urinary tract infections. A healthy vaginal pH is relatively acidic (pH 3.8-4.5). An acidic pH also discourages undesirable bacteria.
In one study (Mijac, 2006), women with yeast were found to have almost as many of the beneficial, hydrogen peroxide producing lactobacilli as women without infections (77% vs 80% respectively). By contrast, women with trichomoniasis had 63%, and those with bacterial vaginosis (BV) were found to have only 25.6% ! In all categories, women who smoked had fewer of the beneficial lactobacilli than nonsmokers.
Women have tried various home remedies to increase lactobacilli numbers in their vagina. Use of natural yogurt as a douche or on a tampon has been advocated. Yet studies suggest that the type of lactobacilli in yogurt lack both the hydrogen peroxide producing qualities, and an ability to cling to vaginal membranes. In a recent experiment (Larsson, 2008) women treated for BV were given 10 days of freeze dried human lactobacilli, or a placebo, as a vaginal capsule. After three months of this treatment the researchers found that the lactobacilli treatment was most effective in preventing relapse of BV in women who were initially cured using antibiotics.
Group B strep, E. Coli, and Staph aureus (normal skin bacteria) were frequently cultured in a group of 631 women, many of whom had no symptoms (Donder, 2002). In a study of 141 GYN surgical patients, Group B strep was found in the vaginal secretions of 20% (Song, 1999). This suggests that many types of bacteria can be a part of the vaginal ecology.
To summarize, normal discharge has a pH of less than 4.5, no overt malodor, a thick or clumpy appearance, and white color. These characteristics can vary over a menstrual month depending upon hormones, changes in pH, brief overgrowths of different species of normal vaginal bacteria, and exposure to semen or menstrual flow.
How often does discharge change?
Among 26 women followed for two months, only four maintained “normal” vaginal conditions. Eight had intermittent yeast (“candida”) overgrowths. Nine had intermittent overgrowth of BV linked bacterias, while one other had BV all month long. Interestingly, many women complained of abnormal discharge or other signs of vaginitis, but symptoms did not correlate to lab testing (Priestly, 1997). Among a different group of 51 women, 22% maintained a “normal” vaginal environment with high levels of lactobacilli. The other 78% had significant but transient changes in their vaginal ecosystem (Schwebke, 1999).
A much larger study of 1,193 women was conducted over three years. About 20% of those women developed BV after 6-12 months. Surprisingly about 20% who had BV at the beginning of the study had no evidence of BV infection at the next follow up exam.
Such studies suggest that many bacterias and fungi (yeast) found in normal vaginal secretions can either overgrow and provoke symptoms – or can return to very low levels where they do not produce ill effects.
Do hormones make a difference in vaginal discharge?
Hormones are one variable which can change over the course of a month. We know that estrogen improves vaginal pH by increasing lactic acid production by vaginal cells. Increased levels of estrogen are also responsible for the increased amount of clear, stretchy cervical secretions seen around ovulation. After ovulation, discharge tends to become less watery and may look more like library paste in its consistency.
Conversely, in a post-menopausal woman who has low levels of estrogen, her vagina is more likely to contain gram positive cocci (e.g. staph aureus, staph epidermis, group A strep) and gram negative rods (e.g. proteus, E Coli). Her vaginal pH will be more alkaline, and there will be fewer of the beneficial lactobacilli bacteria. There will be diminished vaginal secretions, and decreased vaginal lubrication during sex. One innovative study (Gorodeski, 2005), determined that the effects of estrogen on the vaginal ecology differed depending upon the age of the vaginal tissues. This suggests that estrogen’s effects work directly on vaginal cells, not just by encouraging beneficial bacteria and inducing an acidic pH.
What about douching or washing?
Douching has been linked to increased incidence of BV in many, but not all studies. One of the better studies also examined the reason for douching. It would make sense that if one had the malodorous BV discharge that douching might be tried to temporarily get rid of the smell. Of the 1200 women studied, douching for hygiene, as well as for symptoms, both shared an increased incidence of BV. While douching once a month incurred an increased risk of having BV, those who had douched within the past week had the highest risk of all. Women who douched also had decreased concentrations of the beneficial lactobacilli bacteria (Ness, 2002). More recently (Brotman, 2008), it was determined that incidence of BV could be decreased if women refrained from douching for hygiene purposes after menstruation.
Among sex workers in Kenya, women who used any type of vaginal washing (as compared to no washing) had an increased risk for HIV was present after ten years of follow up. The greatest risk was to women who used soap or other substances for cleaning the inside of the vagina rather than plain water (McClelland, 2006).
Type of external cleansing techniques (e.g. soap vs water vs antiseptics) did not predict incidence of candida (yeast) infections in 1004 women cultured for yeast (Oliveira, 1993). This suggests that external cleaning choices do not impact vaginal ecology.
Does my choice of birth control have an impact?
It should come as no surprise that the answer to this question is, “Yes, probably so.” Birth control pills do not change the numbers of beneficial lactobacilli, keep the pH at about 4.4, and do not change the thickness of protective vaginal skin cells (Eschenbach, 2000). Over all the risk for BV is about 50% less in birth control pill users (Calzolari, 2000). Yet the risk for yeast infections is increased when birth control pills are used (Baeten 2001, Fosch 2006)).
Women who wear the NuvaRing have the same healthy vaginal pH as Pill users, but they may have 2-3 times more hydrogen peroxide producing lactobacilli (Vernes, 2004). One study has shown that several subtypes of vaginal yeast can adhere to the NuvaRing (Camacho, 2007), but an increased risk for yeast infections has not been reported. Should a Ring user develop yeast, use of either a cream or suppository antifungal medication does not decrease the Ring’s effectiveness as a birth control method (Verhoeven, 2004).
By contrast, DepoProvera can decrease hydrogen peroxide producing bacteria within six months of use. There can also be a slight thinning of the tissues which keep vaginal pH acidic (Miller, 2000). These effects are likely related to the degree in which DepoProvera decreases estrogen levels. In some women blood estrogen levels can be depressed enough to impact bone density and vaginal symptoms – while in others blood estrogen levels remain well within the usual range.
The use of a copper IUD has been linked to increased BV in four studies. One study (Avonts, 1990), which followed women for two years, found that 50% of IUD users developed BV as compared to 20% of birth control pill users. More recently Ocak and colleagues (2007), followed IUD wearing women for three years. Similarly, it was shown that BV was more common in IUD wearers (11.7%), than in birth control pill consumers (5.9%) or women using neither method (2.9%).
When barrier methods of birth control are utilized there is a spectrum of effects on vaginal ecology. Condoms without spermicide do not change vaginal pH or bacterial parameters. Condoms may protect the vagina from any bacteria present in the ejaculate. However, use of the common spermicide nonoxynol 9 may predispose a woman to abnormal bacterial changes. When used with a diaphragm or cervical cap, this spermicide can transiently decrease lactobacilli, and increase the proportion of E. Coli, enteroccoccus, and anaerobic gram negative bacteria (Gupta, 2000).
You should now be able to make more informed choices about your own vaginal health. As always, seeing a GYN or family planning clinic will yield the most accurate diagnosis and advice.