Diagnosing vaginal infections

Dr Gill Jenkins discusses the common causes of vaginal symptoms and how to diagnose them.

Vaginal candidiasis may present with lumpy discharge and swelling (Photograph: ISM/SPL)
Vaginal candidiasis may present with lumpy discharge and swelling (Photograph: ISM/SPL)

Women with vaginal infection (vaginitis) commonly present with excessive, abnormally discoloured discharge, malodour, irritation, itch, swelling and discomfort. Irregular or unexpected bleeding and abdominal pain may indicate the presence of more serious disease.

The clinical picture, through a precise history and genital examination, will usually reveal the cause, but diagnosis can be confirmed by tests such as high vaginal swab (in charcoal medium), nucleic acid amplification test (NAAT) vaginal swab, and viral or bacterial swabs of suspect ulcerative lesions. Serology may be necessary where the picture indicates syphilis. Urinalysis is essential where bacterial UTI is suspected.

The causative organisms can be divided into sexually transmitted and non-sexually transmitted. Overproliferation of commensal organisms, most commonly candidal yeasts such as Candida albicans, and commensal bacteria in bacterial vaginosis (BV), can cause vaginal symptoms in otherwise healthy women of any age. These overgrowths, if mild and left untreated, may settle as the balance of microbial populations return to normal.

1. Candidiasis

In vaginal candidiasis (thrush), women may notice discomfort, labial swelling, itchiness and a white/cream lumpy, musty smelling discharge, often causing dyspareunia but no systemic upset.

Diagnosis, made by history and examination, is confirmed by high vaginal swab.

Self-care involves wearing cool, loose-fitting, natural fibre clothing and avoiding perfumed bath products. Self- management with natural yoghurt, orally or intravaginally, has no supportive clinical evidence, but there is anecdotal evidence that it may be effective.1,2

Antifungals are available as cream or vaginal pessaries, or orally, and may be used as short courses, prophylactically (for example, when taking antibiotics) or as maintenance therapy.3 Concurrent treatment of the partner may be considered, although there is no evidence to support this if the partner is asymptomatic.4,5 Antihistamines may be useful, especially in women who have concurrent eczema.

Persistent or recurrent candidiasis should prompt diabetes screening, immunity screening and consideration of a change in estrogen status, such as pregnancy or starting HRT.

2. Bacterial vaginosis

In BV there is overgrowth of the commensal population of a mixture of anaerobic, micro-aerophilic and CO2-dependent bacteria, most commonly Gardnerella vaginalis and Prevotella spp, alongside a fall in the commensal lactobacilli population.

In 50% of women, Bacteroides, Mobiluncus spp, Mycoplasma hominis and Ureaplasma spp may also have a role. Presentation is variable, from minimal symptoms to more extensive discomfort with a watery, fishy-smelling grey-green discharge.

Diagnosis is usually made from the history, but an amine test will be positive and dry slide samples may show 'clue cells' – epithelial cells densely covered with bacilli.

BV will respond to a course of oral metronidazole, topical clindamycin, or douching therapy with povidone-iodine.3

Other commensals, such as group B streptococcus, can also cause localised irritation and inflammation. They are diagnosed on culture from vaginal swab and may require antibiotics.

3. Trichomoniasis

The anaerobic single-cell protozoan Trichomonas vaginalis can cause a heavy, frothy, yellow-green, fishy-smelling vaginal discharge, with dysuria and even abdominal pain.

Diagnosis is confirmed by high vaginal swab and the infection should respond to treatment with metronidazole.3

4. Chlamydia

The most common STI in the UK, Chlamydia trachomatis, is asymptomatic in 70% of women and 50% of men, but dysuria, discharge, or irregular bleeding indicate screening.

Testing is widely available in surgeries, clinics and pharmacies through the free National Chlamydia Screening Programme, using NAAT on first-catch urine specimens in men and self-sampled vaginal swabs in women. Treatment is with antibiotics such as azithromycin or doxycycline.

Rarer serotypes of chlamydia, L1, L2 and L3, cause a tropically acquired disease, lymphogranuloma venereum.

5. Gonorrhoea

Infection with Neisseria gonorrhoeae may cause green, bloodstained discharge, dysuria, irregular menstrual bleeding, abdominal pain and fever within two weeks of contact, but some women will remain asymptomatic.

The NAAT test covers gonorrhoea and chlamydia. There has been a rise in penicillin-resistant Neisseria, so treatment is usually a single-dose injection of ceftriaxone, with 1g oral azithromycin. Cefixime is an alternative if injection is refused or contraindicated.3

6. Genital herpes

HSV types I and II can be passed on during sexual activity. The characteristic acutely painful, blistering genital lesions may be associated with fever, tiredness, dysuria and abdominal pain. Viral swab culture confirms the diagnosis. Treatment with antivirals shortens the duration of this often relapsing illness and is most effective if used at the first sign of recurrence.3

7. Genital warts

Genital warts are caused by several strains of HPV, most commonly 6 and 11. Soft, painless growths appear over the skin and mucous membranes of the genital area, taking months or years to grow. If vaginal, they may remain unnoticed. Genital warts can be caused by strains of HPV other than those responsible for cervical cancer.

Diagnosis is by clinical inspection. Treatments include podophyllotoxin, trichloroacetic acid paint, imiquimod cream, laser, cryotherapy, surgical removal or electrical ablation and can take up to three months.3

8. Syphilis

The incidence of Treponema pallidum infection is increasing.6 Stage 1 (primary syphilis) presents with a painless but highly infectious genital sore lasting several weeks. Diagnosis is made by swabbing the sore, if present, or by blood analysis for antibodies. Management, usually with penicillin, should be through a specialist centre.3

  • Dr Jenkins is a GP in Bristol
  • An accurate sexual history is vital. Screening for STIs is essential when symptoms persist.
  • Although initial treatment of simple infection may be appropriate without culture, symptomatology can be variable and the gold standard should be a positive culture and sensitivity, especially with persistent or recurrent symptoms.
  • Atrophic vaginitis in the periand postmenopausal woman can mimic local infection.


1. Pirotta M, Gunn J, Chondros P et al. Effect of lactobacillus in preventing post-antibiotic vulvovaginal candidiasis: a randomised controlled trial. BMJ (Clinical research ed) 2004; 329 (7465).

2. Falagas ME, Betsi GI, Athanasiou S. Probiotics for prevention of recurrent vulvovaginal candidiasis: a review.
J Antimicrob Chemother 2006; 58(2): 266-72.

3. British Association for Sexual Health and HIV Guidelines

4. Bisschop MP, Merkus JM, Scheygrond H et al. Co-treatment of the male partner in vaginal candidosis: a double-blind randomized control study. BJOG 1986; 93(1): 79-81.

5. Fong IW. The value of treating the sexual partners of women with recurrent vaginal candidiasis with ketoconazole. Genitourin Med 1992; 68(3): 174-6.

6. Health Protection Agency


Faculty of Sexual & Reproductive Healthcare Clinical Guidance.
Management of Vaginal Discharge in Non-Genitourinary Medicine Settings
Clinical Effectiveness Unit. 2012

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