The Basics - Vaginal discharge

It is important to establish the cause of this common symptom, explains Dr Louise Newson.

Vulvovaginal candidiasis is caused by Candida albicans (Photograph: SPL)
Vulvovaginal candidiasis is caused by Candida albicans (Photograph: SPL)

Concern about vaginal discharge is the reason for many GP consultations. The majority of causes are physiological discharge and vaginal infections. The history of a woman who presents with a vaginal discharge should include the following:

  • Characteristics of discharge (colour, consistency, duration).
  • Presence of any associated symptoms (pain, itching, fever).
  • Any precipitating factors (before menstruation, after intercourse).
  • Contraceptive, reproductive and sexual history (if relevant).
  • Any co-existing medical conditions.

The examination should include:

  • Abdominal examination (for any localised tenderness).
  • Vulval examination.
  • Bimanual vaginal examination.
  • Speculum examination.

Swabs should be taken as appropriate, depending on history and clinical findings.

1. Physiological discharge
Physiological discharge varies with the menstrual cycle and may be altered by hormonal or intrauterine contraception.

It is usually odourless and clear.

It is most commonly a diagnosis of exclusion.

Factors increasing the volume of discharge include sexual arousal, cervical ectropion and ovulation. At the time of menarche there will be a quite sudden increase in physiological discharge.

Pregnancy can also cause an increase in normal physiological discharge. After the menopause the normal amount of vaginal discharge decreases as estrogen levels fall.

The normal commensal bacterium in the vagina is lactobacillus, which metabolises glycogen in the vaginal epithelium to produce lactic acid, thus creating an acidic environment.

Treatment is usually reassurance. If a cervical ectropion is causing excessive discharge then cautery (for example, by cryotherapy) may be considered as a treatment option.

2. Infective and non-infective causes
The history and examination is important to exclude the following causes of vaginal discharge:

  • Foreign bodies (for example, retained tampons, condoms).
  • Chemical irritants (for example, spermicides, lubricants).
  • Cervical ectropion and polyps.
  • Malignancies (vulva, vagina, cervix, endometrium).
  • Atrophic vaginitis.
  • Post gynaecological surgery (can persist for up to six weeks).

Abnormal vaginal discharge is most commonly caused by an infection.1

These can be non-sexually transmitted or sexually transmitted.

Symptoms suggesting an infection are itching, soreness, smell or profuse discharge.

3. Vulvovaginal candidiasis
Vulvovaginal candidiasis is caused by an overgrowth of yeast, usually Candida albicans. C albicans is actually a normal vaginal commensal organism found in 10-20 per cent of asymptomatic women. Treatment is therefore only indicated if a woman is symptomatic.

Precipitating factors for thrush include recent broad spectrum antibiotics, local irritants (for example, soap or spermicides) and wearing tight synthetic clothing. Risk factors for thrush include a history of diabetes, iron deficiency, corticosteroid use and immunodeficiency.

4. Bacterial vaginosis
Bacterial vaginosis is the commonest infective cause of vaginal discharge. Its prevalence has been reported as 5 per cent in a group of asymptomatic college students, 12 per cent in pregnant women attending an antenatal clinic and 30 per cent in women undergoing termination of pregnancy.

It is more common than thrush. It classically presents with a thin white or grey watery discharge with an offensive fish-like odour. This discharge can be very profuse in some women. However, up to 50 per cent of cases are actually asymptomatic.

Bacterial vaginosis is characterised by an overgrowth of anaerobic organisms that replace the normal lactobacillus. This leads to the pH in the vagina increasing. Common organisms include Gardnerella, Prevotella, Mycoplasma hominis and Mobiluncus.

Bacterial vaginosis is more common in women:

  • with an earlier age of first intercourse;
  • with a higher number of sexual partners;
  • of African origin;
  • who smoke;
  • using intrauterine contraception.

Precipitating factors include menstrual period (blood is alkaline), sexual intercourse (semen is alkaline), a change in sexual partner, which may alter the normal flora of the vagina, and excessive washing, which can also alter the normal flora of the vagina. Treatment is only indicated in women who are symptomatic. Bacterial vaginosis can occur and also remit spontaneously.

The diagnosis of candida and bacterial vaginosis can be based on symptoms, pH and signs.2 Swabs are not always necessary.

5. Sexually transmitted infections
Chlamydia trachomatis is the most common bacterial STI in the UK.3 Although it is usually asymptomatic, it may present with abnormal vaginal bleeding, vaginal discharge, dyspareunia or dysuria.

Neisseria gonorrhoeae is the second most common bacterial STI in the UK. Up to 50 per cent of affected women have a vaginal discharge, this is usually with an associated cervicitis. There may also be pelvic pain and dysuria.

Trichomonas vaginalis is a flagellated protozoon that usually causes a thin frothy yellow discharge with an offensive fish-like odour. There is often associated vaginitis and dysuria. However, many women are asymptomatic. On examination there may be a strawberry appearance of the cervix.

The diagnosis of an STI should lead to adequate patient education and counselling. Other STIs should also be screened for, and contact tracing should be undertaken.

The treatment of vaginal discharge obviously depends upon the underlying cause.

  • Dr Newson is a GP in the west Midlands
Key points
  • Vaginal discharge is a very common symptom.
  • Abnormal vaginal discharge can be associated with other symptoms.
  • Bacterial vaginosis is the commonest infective cause.
  • Diagnosis of candida and bacterial vaginosis can be made on clinical symptoms.
  • STIs should be screened for, if appropriate.

References
1. Clinical Knowledge Summaries. Vaginal discharge. 2009. www.cks.nhs.uk/vaginal_discharge/management/scenario_vaginal_discharge#-367639

2. Health Protection Agency. Management of abnormal vaginal discharge in women. Quick reference guide for primary care for consultation and adaptation. Health Protection Agency 2007.

3. FFPRHC and BASHH. The management of women of reproductive age attending non-genitourinary medicine settings complaining of vaginal discharge. J Fam Plann Reprod Health Care 2006; 32(1): 33-42.

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