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Case History

image A 28-year-old woman presents with a six-week history of an offensive vaginal discharge. She is sexually active and takes the combined oral contraceptive (COC) pill.

What are the important aspects of the history?

What is the differential diagnosis?

What are the treatment options?


image Vaginal discharge is a common presenting symptom and there are a range of possible diagnoses. Causes may broadly be divided into physiological and pathological.

Physiological discharge

Lactobacilli form the normal vaginal flora and colonize the vaginal epithelium. They maintain a vaginal pH of 3.8–4.4 and play a role in the defence against infection. Normal vaginal discharge is altered by a number of factors such as hormonal changes as part of the menstrual cycle, pregnancy and hormonal contraception. Physiological discharge is usually clear or white and odourless.

Pathological discharge


Infections causing an alteration in vaginal discharge may or may not be sexually transmitted (Figure 32.1). Sexually transmitted infections are dealt with in more detail in Case 35: Sexually Transmitted Infections, and would include Trichomonas vaginalis, Neisseria gonorrhoea and Chlamydia trachomatis. Ulceration from Herpes simplex may also result in a vaginal discharge.

Figure 32.1

Diagnosis of candida and bacterial vaginosis. HVS, high vaginal swab. Source: Smellie et al. 2006.8

Bacterial vaginosis (BV) is a common cause of vaginal discharge and results from a change in bacterial flora of the vagina from mainly lactobacilli to high concentrations of anaerobic bacteria. The main bacterium found in BV is Gardnerella vaginalis, although this can be found on culture in approximately 50% of healthy, asymptomatic women.1 Replacement of lactobacilli leads to an increase in vaginal pH to as high as pH 7. Although BV is not regarded as a sexually transmitted infection, it is more common in sexually active than non-sexually active women. It is also more prevalent in black women than white, those with an intrauterine contraceptive device and those who smoke.2

What are the important aspects of the history?

The main complaint is of an offensive, fishy-smelling discharge, usually in the absence of pain or irritation. On speculum examination there is usually evidence of a thin white or grey homogeneous discharge.

What is the differential diagnosis?

Several diagnostic tests exist and a high vaginal swab should be taken from the posterior fornix. Application of the Amsel criteria3 is the gold standard but is not always available in practice. At least three of the four criteria must be present for a diagnosis to be confirmed:

  1. Thin, white homogeneous discharge

  2. Clue cells on microscopy of wet mount

  3. pH of vaginal fluid >4.5


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