Identifying causes of vaginal discharge

Vaginal discharge is a normal aspect of female physiology - however, causes a great degree of anxiety and is a common presentation in general practice. 

Normal vaginal discharge

Normal physiological vaginal discharge plays an essential role in maintaining the vaginal milieu, providing lubrication, removing dead cells and protecting against infection. An individual’s normal vaginal discharge can vary over the lifetime and can change depending on hydration status, use of hormonal contraceptives, the menstrual cycle and menopausal status. Normal discharge is typically clear or white and may be sticky, watery or gel-like.

It is essential to empower women to recognise their normal vaginal discharge to be able to identify when changes occur.

Screening pathological vaginal discharge

Changes in the colour, volume, consistency or smell can indicate pathological vaginal discharge. Many conditions causing unusual vaginal discharge can be diagnosed clinically, so the general practitioner must be aware of the common causes of pathological vaginal discharge and their clinical findings.

In any woman presenting with unusual vaginal discharge, it is important to take a full history, including associated symptoms, cervical smear history, and sexual history. Clinical examination is essential, including pelvic examination and speculum examination. The cervix should be visualised, and a sample of the discharge should be obtained. A cervical smear should be obtained opportunistically if due. The clinician should be alert for more unusual presentations such as retained foreign body.

Causes of unusual vaginal discharge

Bacterial vaginosis

Bacterial vaginosis (BV) is one of the most common causes of abnormal vaginal discharge. BV typically presents with a grey or off-white discharge, often with a fishy odour. BV is caused by an imbalance in normal vaginal bacterial flora, resulting in a reduction in lactobacilli, an increase in vaginal pH and an overgrowth of anaerobic bacteria. Vaginal pH can be measured in the clinic using narrow-range pH paper, where a pH of greater than 4.5 suggests BV. Where microscopy is available, clue cells are a reliable diagnostic sign of BV.

BV can resolve spontaneously or may require treatment using oral or intravaginal antibiotics.

Candida infections

Candida infections typically present with a lumpy white “cottage cheese” discharge, often with associated irritation or itching and is caused by overgrowth of fungal species such as candida albicans. Candidiasis can be diagnosed clinically where typical signs and symptoms are present. Microscopy reveals budding yeast or hyphae.

Treatment is with oral or intravaginal antifungal medication.

STIs

Sexually transmitted infections, such as chlamydia, gonorrhoea, trichomoniasis and mycoplasma genitalium, when symptomatic, may cause a change in vaginal discharge, which may be green or yellow. Other symptoms may include pelvic pain and unscheduled vaginal bleeding. Chlamydia and gonorrhoea are typically diagnosed using a nucleic acid amplification test (NAAT) and treated using antibiotics.

Unscheduled vaginal bleeding

Brown, red, pink or black vaginal discharge may be a sign of underlying unscheduled vaginal bleeding. Unscheduled vaginal bleeding may be indicative of infection, hormonal changes or cervical pathology (including cervicitis, cervical dysplasia or malignancy). In these cases, it is essential to investigate the unscheduled bleeding and refer to secondary care where appropriate.

Unusual vaginal discharge is common and causes significant anxiety in women attending the general practitioner. In many cases, vaginal discharge may be physiological. Where discharge is pathological, a careful history and clinical examination can often delineate the underlying cause, and treatment can be often be initiated immediately.

Dr Samantha Miller, MBChB

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Read another article like this one: HPV in women's health

References

•    Kairys N, Carlson K, Garg M (2024). Bacterial Vaginosis. In: StatPearls. https://www.ncbi.nlm.nih.gov/books/NBK459216/ 
•    R AN, Rafiq NB (2023). Candidiasis. In: StatPearls. https://www.ncbi.nlm.nih.gov/books/NBK560624/ 
•    HealthDirect (2023). Vaginal Discharge. https://www.healthdirect.gov.au/vaginal-discharge 
•    Sexual Health Victoria (2021). Vaginal Discharge. https://shvic.org.au/for-you/genital-health/vaginal-discharge 
•    Royal Australian College of General Practitioners (2011). Odorous vaginal discharge A case study for thorough investigation. https://www.racgp.org.au/afp/2011/august/odorous-vaginal-discharge 
•    Melbourne Sexual Health Clinic (2021). Vaginal discharge treatment guidelines. https://www.mshc.org.au/health-professionals/treatment-guidelines/vaginal-discharge-treatment-guidelines