‘Doctor, I’ve got thrush again.’ A guide to vaginal discharge

Many women, and all too frequently their doctors, think that every complaint of vaginal itch, discomfort or discharge is due to a Candida infection, colloquially known as ‘thrush’. (Interestingly, this term is so common that the first items to come up in a Google search of ‘thrush’ all relate to Candida rather than birds.) Although some Candida species do cause vaginal discharge, there are many different causes of discharge, some of which require treatment and all of which benefit from an accurate diagnosis.

What can the history tell you?

In women presenting with a complaint of vaginal discharge, the following information can be invaluable in deciding which tests might need to be carried out. Ask the patient:

• What colour is the discharge? Is it thick or runny?  Is there any odour?
• Is there any itch (do you need to scratch) or burning  (sore, not itchy)? 
• Is there any abnormal bleeding or change in menstrual pattern?
• How long have you had this problem?
• Have you ever had this problem in the past?
• Is there any pattern to the discharge, for example, related to your menstrual cycle or sexual activity? 
• Have you ever had any tests done? What did they show?
• What treatment have you tried? Was it prescribed by a doctor or over the counter?

It is also prudent to enquire about sexual partners and sexual activity. Depending on the relevance, condom usage and contraception could be asked about. Ask the patient:

• Have you had any change in sexual partner recently? 
• Is your partner male or female?
• Do you have any pain in the pelvis, with or without sex?

Why do I need to examine the patient, can’t I just do tests? 

It is wise to examine any woman who presents with a complaint of vaginal discharge, starting with a visual inspection of the external genitalia. A profuse thick or thin discharge, erythema or scratch marks might give an indication of the diagnosis. Next, a speculum examination of the vagina is needed (in some patients with Candida albicans this might not be possible due to excessive discomfort). It is useful to look at the discharge in situ and to observe the following: 

• What is the colour and volume of the discharge? 
• Does the discharge appear to be coming through the cervix or is it vaginal? 
• Is there any blood associated with the discharge?
• What does the cervix look like (colour, texture, cell types visible, ulceration)?
• What does the vagina look like (colour, adherent discharge, ulceration)?

If there is no discharge present when the patient is examined, consider giving her a take-home swab (with instructions on how to use it) and/or advise her to make an urgent appointment when the discharge returns. 

After removing the speculum, a bimanual examination to check for cervical excitation and to determine whether there is tenderness over the fallopian tubes is wise (if there is any complaint of lower abdominal or pelvic pain) to avoid missing a diagnosis of pelvic inflammatory disease.

What tests should I do? 

The choice of test depends on whether you have carried out any tests for this patient in the past; on the patient’s answers to your questions; and on your examination findings. 

In women presenting with a complaint of vaginal discharge, and who are sexually active, it is useful to test for sexually transmissible infections, even if in a regular relationship. Some infections, such as Chlamydia trachomatis, can persist for years and more recently recognised infections, such as Mycoplasma genitalium, may never have been tested for. If these are missed the patient may develop a pelvic infection. The choice of test depends on clinical judgement. Options are listed in Box 1. 

What is the likely diagnosis, and how do I manage it? 

There are many different causes of vaginal discharge, including chlamydia, gonorrhoea, M. genitalium, Candida spp., bacterial vaginosis and Trichomonas vaginalis. Table 1 describes the different causes of vaginal discharge and their associated characteristics.

Management depends on the clinical findings and test results. Chlamydia and gonorrhoea are laboratory notifiable infections and the doctor’s responsibility includes a discussion with the patient about contact tracing so that their partner/s can be tested and treated. M. genitalium and T. vaginalis are not notifiable but are sexually transmissible, so contact tracing and treatment of partners is required. Management options, listed by infection type, are outlined in Table 2. 

A case scenario that illustrates the recommended investigation and management of a woman with a vaginal discharge is shown in Box 2.

Conclusion

In women presenting with an abnormal vaginal discharge, time should be taken to explore the symptoms and examine the patient. Swabs for microscopy, culture or nucleic acid amplification testing can guide treatment of an acute or recurrent problem. Chlamydia is the most common notifiable infectious disease in Australia. It is important not to miss this diagnosis as it can have long-term clinical implications for the patient (as well as being a public health issue). It is also important to remember the value of contact tracing for sexually transmissible infections to reduce reinfection (this is also a public health obligation). 

If a patient has a problematic vaginal discharge that cannot be managed in primary care, seeking advice or referring the patient to a sexual health clinic or gynaecologist is recommended.      MT

Further reading