Abnormal vaginal discharge - red flag symptoms

Red flag symptoms in patients with vaginal discharge, including possible causes and how to identify these.

Vaginitis and leucorrhoea caused by trichomoniasis (Photo: Dr Isabelle Cartier/ISM/Science Photo Library)
Vaginitis and leucorrhoea caused by trichomoniasis (Photo: Dr Isabelle Cartier/ISM/Science Photo Library)

Red flag symptoms

  • Recent change in sexual partner
  • Blood stained discharge
  • Post-coital bleeding
  • Associated lower abdominal pain and fever
  • History of intermenstrual bleeding
  • Foul smelling discharge

Vaginal discharge is most common in women of reproductive age but can also present in pre-pubertal females, during pregnancy and in postmenopausal women. Causes of vaginal discharge can be categorised as physiological, infective (non-sexually), infective (sexually) and non-infective.


Questions to ask include:

  • Is the discharge new? If not, why has the patient presented now - has it changed in colour, frequency or odour? If it is new, the history of the discharge is important, together with a sexual history.
  • Has the patient had a recent sexual health screen? If so, what were the results? Is there a history of sexually transmitted infections (STIs)?
  • Has there been a recent change in partner?
  • Is the patient using contraception?
  • Are there are any associated symptoms such as itch, superficial or deep dyspareunia, lower abdominal pain or fever?
  • Is the discharge blood-stained?
  • Is there postcoital bleeding or menstrual irregularity?
  • Are the patient's smears are up to date?
  • How is it affecting the patient’s quality of life?


Examination is essential if a cervical aetiology, STI, pelvic inflammatory disease (PID) or non-infective cause is suspected. You may need to take triple swabs to exclude infection. If PID is suspected, you may wish to perform abdominal palpation and speculum to test for cervical excitation. If a simple candidiasis is suspected, it is reasonable to test this hypothesis with appropriate treatment, and consider swabs if the symptoms are not improving.


First pass urine can be used as an alternative investigation to swabs for chlamydia and gonorrhoea. Asking the patient to perform a self vaginal swab is also becoming more common. Check with your laboratory that this type of testing is approved and ensure you are aware of the right swabs and containers to use for the urine samples.

If a patient is experiencing recurrent candidiasis, you may wish to measure HbA1c to exclude diabetes.

Possible causes of vaginal discharge
  • Bacterial vaginosis
  • Candidiasis
  • Diabetes mellitus
  • Toxic shock syndrome
  • Chlamydia, gonorrhoea or trichomoniasis
  • Cervical pathology
  • Pelvic inflammatory disease (PID)
  • Rectovaginal fistula

Possible causes


Physiological causes are common and consist of cervical mucus, local bacterium, secretions and menstrual fluid. In women of reproductive age, fluctuating levels of oestrogen and progesterone contribute to this. It is generally non-offensive and often white or clear.

Infective (non-sexually)

The two infections in this category are bacterial vaginosis and candidiasis.

Bacterial vaginosis tends to present with a fishy-smelling discharge and is caused by an overgrowth of anaerobic bacteria replacing the normal vaginal flora, leading to an increase in pH. Microbiology will often report "clue cells seen". Treatment is with metronidazole.

Candidiasis is a common presentation and patients may say that they have thrush, based on previous experience. The discharge is often white and there may be associated itch. Candidiasis can be triggered by use of antibiotics, steroids or long-term immunosuppressants. Think about underlying immunosuppression or consider diabetes mellitus if the infection persists.

Infective (sexually)

Infections include chlamydia, gonorrhoea and trichomoniasis. These are transmitted sexually, so the patient's history may guide diagnosis. If detected, patients require prompt treatment, screening for other STIs, partner notification and/or contact tracing. Chlamydia is a common STI which is often present without symptoms but can lead to PID. Treatment is usually with doxycycline or azithromycin. Acute PID can present with significant sepsis and septic shock thus urgent admission may be necessary. Other complications of PID can include infertility, abscess and ectopic pregnancy. When managing patients with PID, make them aware of the increased risk of ectopic pregnancy for future pregnancies.


This category includes foreign bodies such as retained tampons (which can cause toxic shock syndrome) or condoms, cervical ectopy, polyps and genital tract malignancy. Allergy to lubricants or spermicides can also present with vaginal discharge. Rectovaginal fistulas are a rarer cause of vaginal discharge and would require urgent discussion with the surgical team.

  • Dr Singh is a GP in Northumberland

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