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March 2008: Which patients with vaginal discharge should be referred?

What are the main causes of vaginal discharge?

How should patients be assessed?

How should vaginal discharge be treated?

It is normal for women of reproductive age to have a physiological vaginal discharge. This is part of a self-cleansing mechanism and alters as oestrogen and progesterone levels vary throughout the menstrual cycle.

About four days before ovulation, it becomes clear, slippery and stretchy (the consistency of raw egg white), and changes rapidly once progesterone starts to act on it, becoming thick, white and tacky.

In addition, lactobacilli in the vaginal walls metabolise glycogen (under the influence of oestrogen), producing lactic acid (pH around 4.5) and thus protecting the vagina and uterus from pathogens.

The amount of discharge varies from woman to woman and it is normal to find yellowish staining on underwear.

In prepubertal children, vaginal discharge is not normal. When it occurs it is usually associated with a mixed growth of faecal organisms.1

In postmenopausal women, a thin, greyish-white discharge may be present. The lack of oestrogen (and hence lactobacilli) results in a change in pH and contamination with bowel bacteria can occur.

Assessment

It is important to establish what the woman's concerns are. In many cases the discharge is physiological and the patient can be reassured. However, it is important to determine when the discharge started and whether it is associated with an unpleasant odour or has changed in colour or consistency.

GPs should ask about associated symptoms, such as superficial or deep dyspareunia, itching or dysuria (see figure 1, attached).

A sexual history needs to be taken, particularly in young women, and GPs should enquire about new partners. Women should also be asked about contraceptive use; the contraceptive pill tends to decrease vaginal discharge, and the intrauterine contraceptive device to increase it.

Recent antibiotic use, diabetes and pregnancy increase the risk of candidiasis. GPs should also consider noninfective causes, such as a foreign body (eg a retained tampon), polyps and cervical ectopy.

Patients with blood staining should be referred urgently to a gynaecologist.

Causes

Non-sexually transmitted infections

Bacterial vaginosis is the most common infective cause of vaginal discharge. It is typically associated with a fishy smell and a thin discharge. Itching is absent. Bacterial vaginosis is caused by an overgrowth of anaerobic bacilli, which replace the lactobacilli, resulting in an increase in vaginal pH (>4.5).

Candidiasis is caused by a yeast infection and leads to a typical thick white discharge often described as resembling cottage cheese. It is associated with itching and soreness and often causes superficial dyspareunia. The vulva is frequently involved. Candidiasis typically occurs when oestrogen levels are high, for example during pregnancy. The lifetime risk is around 50-75%.2

There is no convincing evidence that hormonal contraception, use of tampons or sanitary towels, or vaginal douching increases the risk of candidiasis.

Noninfective causes

Foreign bodies retained within the vagina will result in a discharge, which may become infected.

A retained tampon is a relatively common cause. These often get pushed up into the posterior fornix and may be difficult to see on cursory examination.

In the elderly, ring pessaries may lead to a profuse discharge and a course of topical oestrogen is likely to help.

In both cases, a short course of antibiotics will clear the infection.

Cervical polyps, especially when large, may increase physiological discharge and occasionally cause postcoital bleeding. These can be avulsed painlessly by simply twisting them off.

Cervical ectopy (previously known as erosion) exposes a large glandular area on the vaginal portion of the cervix and subsequently increases discharge. Other, rarer causes include malignancy and fistulae (especially from diverticular disease in older patients).

Sexually transmitted infections

Chlamydia trachomatis is by far the most common STI and can lead to pelvic inflammatory disease, tubal damage and resultant subfertility. It is asymptomatic in about 75% of cases but may cause cervicitis with ensuing discharge. Postcoital bleeding, deep dyspareunia and pelvic pain are all markers of the condition. Women under the age of 25 are particularly at risk. A systematic review found an estimated prevalence of Chlamydia trachomatis of 8.1% in the under 20s, 5.2% in 20-24 year olds, and 2.6% in 25-29 year olds, decreasing to 1.4% in those aged over 30 years.3

Trichomonas vaginalis is not common. It is associated with a frothy, yellowish discharge and a strong odour. It may be accompanied by itching and dysuria.

Infection with Neisseria gonorrhoeae is becoming more common. Half of infected women will have a discharge,4 which is caused by cervicitis. Other pathogens may be present.

Investigation

The Faculty of Family Planning and Reproductive Health Care (RCOG) has issued comprehensive guidelines on investigating women with vaginal discharge (see figure 1, attached).2

In women with a low risk of an STI and no symptoms of infection, treatment should be empirical and based on sexual and clinical history:

• If the discharge is non-offensive, white and itchy, it should be assumed that there is a candidal infection and suitable oral or vaginal antifungals should be prescribed.

• If the discharge is offensive but non-irritant, bacterial vaginosis is likely and suitable treatment should be given.

For all other patients, for example those with recurrent infections, women at increased risk of STIs, during pregnancy (and also for at least two weeks postpartum, post-abortion and after miscarriage) and those with a medical condition such as diabetes, a full pelvic examination should be carried out and triple swabs (chlamydia, high pelvic swab and endocervical swab) taken.

Swabs should be placed in a suitable transport medium and, if there is a delay, stored at 40C. Vaginal pH should be measured and can be checked with narrow range paper (pH 4-7). If the pH is ? 4.5 and there is an accompanying odour, there is a high likelihood of bacterial vaginosis. Candidiasis is associated with a pH <4.5.

If chlamydia is suspected, testing usually involves an endocervical swab. Local laboratory protocols should be used.

Screening using a urine sample is now available over the counter. Neisseria gonorrhoeae testing also involves an endocervical swab, which must be placed in a charcoal-based transport medium. If gonorrhoea is suspected, the patient should be referred to the local GUM clinic.

Treatment

Drug therapy

Vaginal and oral therapies are equally effective in treating candidiasis. A single high dose is as effective as a week's course of low-dose therapy and compliance is likely to be better. Contrary to popular belief, there is no good evidence that treatment of sexual partners is beneficial.

Bacterial vaginosis can be treated with oral metronidazole or vaginal clindamycin for seven days. Both are effective. Again, treating partners does not appear to affect relapse rates.

Trichomonas vaginalis is also treated with metronidazole. In both conditions a single 2g oral dose is effective and likely to improve compliance.

If chlamydia or gonorrhoea is identified, local integrated pathways should be in place for testing, treating and contact tracing.

Probiotics

Live yoghurt contains Lactobacillus acidophilus. A small trial of intravaginal yoghurt with estriol supplements in women with bacterial vaginosis found an 88% cure rate at four weeks compared with 22% in the placebo group.5 Although the available results concerning the effectiveness of the administration of lactobacilli for the treatment of bacterial vaginosis are mostly positive, it cannot yet be concluded definitively that probiotics are useful for this purpose.6

The same authors report that the available evidence for the use of probiotics for prevention of recurrent vulvo-vaginal candidiasis is limited. The empirical use of probiotics may be considered in women with frequent recurrence of vulvo-vaginal candidiasis (more than three episodes per year), especially for those who have adverse effects from or contraindications for the use of antifungal agents, since adverse effects of probiotics are very rare. However, women should be clearly informed about the unproven usefulness of probiotics for this purpose.7

Management problems

Recurrent discharge

Relapse of bacterial vaginosis is relatively common. A number of trials have been conducted with a variety of therapies. Acidifying (lactic acid) gels appear to be an effective treatment when combined with tinidazole.8 Metronidazole 0.75% vaginal gel 5g twice weekly for four to six months is usually curative, especially when combined with an acidifying gel.

Little has been published on the best approach to women with frequent recurrence of bacterial vaginosis. Small studies of live yoghurt or Lactobacillus acidophilus have not demonstrated benefit.9 Douching and the use of shower gel or antiseptics in the bath should be avoided.

Recurrent vulvo-vaginal candidiasis occurs in less than 5% of women. Long-term treatment for six months is effective but relapse within a year is common. GPs should advise patients to avoid wearing close-fitting synthetic undergarments and using vaginal deodorants or other potential irritants.

Vaginal discharge in children

Discharge in children is relatively unusual. However, the vagina of a child is not oestrogenised (except at birth) and therefore lacks lactobacilli. Infection with gut flora can occur, especially if the patient wipes back to front after defaecation.

Tight-fitting synthetic underwear can exacerbate the problem. Oral antibiotics are usually curative.

Bacterial vaginosis is very uncommon in children, and has been associated with sexual abuse, but can occur spontaneously.

Persistent discharge that fails to clear with treatment is usually associated with a foreign body in the vagina. Children often don't admit to putting anything in the vagina and if a foreign body is suspected the patient should be referred to hospital for full examination under sedation or general anaesthesia.

Threadworm infestation is common in children and may involve the vagina, causing pruritus and discharge. Careful examination around the anal area will usually reveal the cause, and treatment is with mebendazole or piperazine. The adhesive tape test is no longer used in primary care.

Referral

Most vaginal discharges can be treated in primary care. However, if there is blood staining associated with the discharge, the patient should be referred to a gynaecologist.

If an STI is suspected, the patient should be referred to the local GUM clinic for treatment and contact tracing. Cases of recurrent discharge where treatment has failed may also need referral to hospital.

Some women may keep returning even though their swabs are normal.

The cause of postmenopausal discharge is usually secondary to a lack of oestrogen. A topical oestrogen intravaginal tablet, cream, pessary or ring is usually curative. Topical oestrogens are not absorbed systemically and can be used safely without an opposing progestogen for at least three months. There is no evidence that longer periods of treatment have any harmful effect.

In other women, it is appropriate to enquire in detail about the nature of the discharge and its relationship to physiological changes. GPs should re-emphasise advice about close-fitting synthetic clothing, douches and vaginal deodorants. It is important to consider whether the symptoms may be related to psychosexual problems or abuse, and discreet enquiries should be made.

Author

Mr Peter Bowen-Simpkins
MA FRCOG FFFP
consultant gynaecologist and Medical Director of the London Women's Clinic

Key points Figure 1: Algorithm for the assessment of women with vaginal discharge Which patients with vaginal discharge should be referred?

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