Vaginal Discharge

Vaginal discharge is the emission of secretions from the vagina. Some mucous secretion from the vaginal walls and the cervix is normal in the reproductive years; its amount and nature vary from woman to woman and at different times in the menstrual cycle (see menstruation). Oral contraceptives can increase or decrease this discharge. Secretions tend to be greater during pregnancy. Sexual stimulation also produces increased vaginal discharge.

Abnormal vaginal discharge 

Discharge may be abnormal if it is excessive, offensive-smelling, yellow or green, or if it causes itching. Abnormal discharge may accompany vaginitis (inflammation of the vagina), which may be the result of infection, such as candidiasis (thrush) or trichomoniasis, or may be due to a foreign body, such as a forgotten tampon, in the vagina.

Vaginal discharge in detail - technical

Vaginal symptoms are a frequent source of discomfort and distress for many women. Bacterial vaginosis, vulvovaginal candidiasis, and trichomoniasis are considered the most common causes in premenopausal women, but atrophic vaginitis and noninfectious disorders seem to occur more often in menopausal women.

Self-diagnosis and syndromic management, although increasingly encouraged in many parts of the world, are fraught with inaccuracy. A proper diagnosis depends on a thorough history, examination, and readily available tests in the clinic. Ancillary tests to be considered in selective circumstances include cultures for trichomonas or yeast, tests for Neisseria gonorrheae or Chlamydia trachomatis, and (rarely) Gram stain or maturation index. Once a proper diagnosis is obtained, appropriate treatment can be selected.


Vaginal discharge, itching, burning, irritation, and odour are common causes of distress in women, yet they are frequently ignored or trivialized by health care providers. With the availability of over-the-counter antifungals, self-diagnosis and self-treatment of vaginal symptoms have become routine, but questions remain about their accuracy. Appropriate tests in the clinic and laboratory are the only reliable basis for treatment.

The normal vaginal environment

An understanding of the normal vaginal environment is crucial to accurate clinical assessment and interpretation of test results. The normal vaginal environment is controlled by a woman’s oestrogen status. By increasing the glycogen content of vaginal epithelial cells, oestrogen fosters the growth of lactobacilli, which in turn seem to inhibit the other growth of other organisms. Thus, a Gram stain of vaginal secretions from a healthy woman in her reproductive years should be dominated by lactobacilli and Gram-positive rods. However, vaginal cultures will yield a broad range of organisms, including skin and faecal flora (e.g. Staphylococcus epidermidis, Staph. aureus, Escherichia coli, anaerobes) and organisms, which in many situations, are considered pathogenic (e.g. Streptococcus agalactiae (group B streptococci), Mycoplasma hominis, Ureaplasma urealyticum, Gardnerella vaginalis, and Candida albicans). In women who are either prepubertal or postmenopausal, lactobacilli are less numerous, and other bacteria will frequently predominate.

Differential diagnosis and clinical investigation

Most studies suggest that infections such as bacterial vaginosis (30–35% of cases), vulvovaginal candidiasis (20–25%), and trichomoniasis (15–20%) are the most common causes of vaginal symptoms, but many miscellaneous conditions, including atrophic vaginitis, vulvar conditions (e.g. vulvodynia, lichen sclerosus, lichen simplex), or even a physiological discharge can cause symptoms that require assessment. A thorough evaluation will usually allow correct diagnosis.

An accurate diagnosis relies largely on the patient’s history. Symptoms are often not limited to discharge alone but frequently include itching, burning, irritation, or malodour. Since patients may be too embarrassed to mention some of these, it is helpful to inquire about each of them in turn. Other pertinent information is about location (vulvar, introital, or vaginal), duration, variation with menstrual cycle, association with sexual activity, and response to previous therapy. A sexual history may identify women at increased risk of a sexually transmitted infection. Pelvic examination should include inspection of the vulva and vestibule; touching the vulva and vestibule with a swab (the ‘Q-tip test’) may elicit areas of tenderness. Samples should be obtained for further evaluation. Vaginal pH testing, an amine (‘whiff’) test, and saline and 10% potassium hydroxide microscopy should be practised routinely. If the source of discharge is primarily the cervix, culture or nucleic acid amplification tests for N. gonorrheae and C. trachomatis should be obtained. Suspected vulvar diseases may require a biopsy for diagnosis. Finally, in situations where the diagnosis is not clear, definitive tests may assist in the diagnosis of bacterial vaginosis, trichomoniasis, and vulvovaginal candidiasis (Table 1).

Table 1 Testing for vaginal infections
  Vaginal pH Amine test Microscopy Gold standard
Normal ≤4.5 Normal  
Bacterial vaginosis >4.5 + Clue cells Gram stain
Trichomoniasis >4.5 ± Trichomonads Trichomonas culture
Vulvovaginal candidiasis ≤4.5 Pseudohyphae, blastospores Yeast culture
Atrophy >4.5 Immature epithelial cells Maturation index


Trichomonas vaginalis is a common sexually transmitted protozoan, causing an estimated 180 million infections per year worldwide. Traditionally, it has been considered a minor nuisance, but it is associated statistically with an increased risk of low birth weight or preterm delivery in pregnant women and of HIV transmission in nonpregnant women. Asymptomatic men and women are the primary reservoir for infection. Affected women will complain of an abnormal purulent, frothy or bloody discharge, itching, malodour, dysuria, urinary frequency, dyspareunia, and postcoital bleeding. Examination may reveal, erythema and excoriations of the vulva or vagina, an abnormal discharge, and punctate haemorrhages of the cervix (the ‘strawberry cervix’). Saline microscopy may reveal motile trichomonads, but it has limited sensitivity (22–75%). Finding many white blood cells on microscopy, a positive amine test, or an elevated pH may suggest the presence of trichomoniasis but do not prove the diagnosis. The current gold standard is culture. Where available, antigen-based tests at the point of care are much more sensitive than microscopy and provide a more rapid answer than culture.

Treatment is with nitroimidazoles, either metronidazole or tinidazole. A single dose of 2 g of either will cure more than 90% of affected cases. Alternatively, a 7-day course of 500 mg twice daily is recommended. As with other STDs, treatment of the partner is crucial to prevent reinfection. Patients who are allergic to metronidazole should be referred for desensitization and then treated with metronidazole. In cases of treatment failure, patient compliance must first be confirmed and reinfection by her partner excluded. Since tinidazole seems to be more effective than metronidazole, higher doses of tinidazole, such as 2 g daily for 5 days, can be considered. Pregnant women with trichomoniasis should receive metronidazole, as there are no data on tinidazole use in pregnancy.

Bacterial vaginosis

This is considered the most common cause of vaginitis, with a prevalence of 5 to 25%. It represents a polymicrobial infection of the vagina. The vaginal flora is markedly altered. Hydrogen peroxide-producing lactobacilli are absent, and there is an overgrowth of a wide variety of organisms, including G. vaginalis, M. hominis, Bacteroides spp., Prevotella spp., Mobiluncus spp., and other bacteria that are still being identified. Bacterial vaginosis is associated with a variety of risk factors, including multiple partners, more frequent sexual intercourse, smoking, and douching. Although it may be sexually transmitted in lesbians, treatment of male partners of heterosexual women has failed to reduce recurrence rates and it has been found in sexually inexperienced women. In nonpregnant women, it has been associated with many conditions including pelvic inflammatory disease, infection after abortion or hysterectomy, cervicitis, urinary tract infection, and HIV and herpes simplex virus-2 transmissions. In pregnant women, studies have linked bacterial vaginosis to prematurity, preterm premature rupture of membranes, and postpartum endometritis.

Although up to 50% of women are asymptomatic, affected women will note an abnormal discharge or a fishy odour, which is often worse during menses or after intercourse. Itching and irritation are considered rare. The clinical criteria (Amsel’s criteria) which are used to diagnose infection consist of the following:

  • a homogeneous grey or white discharge
  • a vaginal pH exceeding 4.5
  • a positive amine test
  • more than 20% clue cells (vaginal epithelial cells stippled with bacteria) on saline microscopy.

Three out of the four criteria are adequate for a diagnosis. Alternatively, a Gram stain (Nugent) score, which evaluates the presence or absence of various bacterial morphotypes, may be used. Because the Nugent score is a permanent record, which can be read by personnel who are blinded to patient information, it is the preferred method of diagnosis in research studies.

Oral or topical treatment seems equally effective.

  • Oral regimens, including metronidazole 500 mg twice a day for 7 days, tinidazole 1 g daily for 5 days, or clindamycin 300 mg twice daily for 7 days, tend to be less expensive but may cause gastrointestinal distress; metronidazole and tinidazole are incompatible with drinking alcohol.
  • Topical regimens, such as 0.75% metronidazole gel (one 5-g applicator daily for 5 days), 2% clindamycin standard (one 5-g applicator daily for 7 days) or single-dose creams (one 5-g applicator), and 100-mg clindamycin ovules (one ovule nightly, for 3 doses) tend to be more expensive.

In high-risk pregnant women, particularly those with prior preterm birth, as well as nonpregnant women undergoing either hysterectomy or abortion, screening and treating for bacterial vaginosis seems to decrease associated morbidities. To date, low-risk pregnant women do not seem to benefit from screening and treatment for asymptomatic bacterial vaginosis. Apart from tinidazole, pregnant women can be treated with similar bacterial vaginosis regimens as nonpregnant women.

Recurrence after treatment seems to occur commonly, up to 50% within 6 months. For patients with frequent recurrences (3 or more per year), a prolonged 4-month course of suppressive antibiotic therapy, such as metronidazole 0.75% gel, one 5-g applicator twice weekly, was associated with much lower rates of bacterial vaginosis than a placebo group. It is claimed that some commercially available products can repopulate the vagina with lactobacilli, but there are no conclusive data to support their use or efficacy in women with recurrent bacterial vaginosis.

Vulvovaginal candidiasis

About 75% of women will at some time in their lives develop vulvovaginal candidiasis or ‘yeast infections’. C. albicans causes 90 to 95% of vulvovaginal candidiasis; of the many other species of yeast that are sometimes implicated, C. glabrata is thought to be the second most common. Commonly recognized risk factors for candidiasis include the use of oral contraceptives, recent use of broad-spectrum antimicrobials, pregnancy, diabetes mellitus, and immunosuppression. Being sexually active and practising oral receptive sex are associated with vulvovaginal candidiasis, but there are no data to support partner treatment. Patients with vulvovaginal candidiasis complain primarily of vulvar or vaginal pruritus, irritation, burning, dyspareunia, or abnormal discharge. The symptom of discharge is quite unreliable in predicting which women with vaginitis actually have vulvovaginal candidiasis. Examination of affected women may reveal vulvar erythema, oedema, excoriations, or fissures. Vaginal thrush may be present. The vaginal pH is normal. On microscopy, hyphae or blastospores may be seen, but the sensitivity is fairly low (c.50%); thus, a simple yeast culture is recommended in women who are symptomatic but with negative microscopy.

For most women with vulvovaginal candidiasis, the infection will be uncomplicated: it is sporadic, associated with relatively mild symptoms, caused by C. albicans, and is occurring in an otherwise normal host. Uncomplicated vulvovaginal candidiasis generally responds readily to any available antimycotic treatment. Topical therapies consist primarily of imidazoles, including miconazole, clotrimazole, butoconazole, and terconazole, which are available as creams or suppositories applied for 1 to 7 days. A single150-mg dose of oral fluconazole seems equivalent to topical treatments.

An estimated 5% will suffer complicated vulvovaginal candidiasis, marked by either an underlying medical problem such as diabetes mellitus or HIV infection, severe symptoms, recurrent disease (four or more episodes per year), or an infection caused by a yeast other than C. albicans. Most of these women will not have any of the commonly recognized risk factors for infection. Complicated vulvovaginal candidiasis will recur within a month in at least 50% of cases, and is best managed by first obtaining a positive yeast culture to obtain information about the species of the isolate, then by more aggressive therapy and follow-up. In patients with severe vulvovaginal candidiasis, a second dose of fluconazole 3 days after the first, or a second week of topical therapy, improves the chance of complete resolution. Women with recurrent vulvovaginal candidiasis caused by C. albicans benefit from prolonged suppressive therapy with weekly oral fluconazole (100–200 mg) after an initial induction phase of 3 doses given 3 days apart. Finally, for C. glabrata infections, boric acid capsules (600 mg vaginally), nightly for 14 days, are often curative.

Atrophic vaginitis

Since women are living longer in many countries, larger proportions of their lives are postmenopausal. As a consequence, atrophic vaginitis, which is caused by a lack of oestrogen, is likely to become increasingly common. Women with atrophy may present with a spectrum of complaints, including an abnormal discharge, dryness, itching, and dyspareunia. Signs of labial atrophy, vaginal pallor, or loss of rugal folds may be easily missed. The vaginal pH will usually be elevated above 4.5. On wet mount, immature epithelial cells; either parabasals or intermediate cells, which are rounder, smaller, and have a greater nucleus:cytoplasmic ratio can be seen. Because of its effects on vaginal flora, there may be a decreased normal flora or even a shift to cocci instead of bacilli.

In the absence of contraindications, oestrogen remains the medication of choice. Topical therapy, in the form of cream, tablets, or an oestrogen ring, will give the highest local levels of oestrogen, while minimizing systemic absorption but not eliminating it. Since oestrogen tends to cause slow improvement, patients should be instructed to adhere to treatment for at least 6 weeks before concluding that it will be ineffective.


Vaginitis is a common problem in women of all ages. Effective therapy is available for the many causes of vulvovaginal symptoms, but will depend on an accurate diagnosis.

Further reading


Anderson MR, Klink K, Cohrssen A (2004). Evaluation of vaginal complaints. JAMA, 291, 1368–79.
Centers for Disease Control and Prevention. (2006). Sexually transmitted diseases treatment guidelines 2006. MMWR, 55, 51–8.