What does the colour and texture of discharge tell you?
The colour, texture and smell of discharge narrow down the likely cause, though only a swab confirms it. Trichomoniasis typically produces a frothy, yellow-green discharge with a strong odour. Chlamydia and gonorrhoea can both cause a yellow or yellow-green discharge, sometimes thicker with gonorrhoea. Bacterial vaginosis (BV) causes a thin, greyish-white discharge with a fishy smell, especially after sex. Thrush causes a thick, white, cottage-cheese-like discharge with intense itching but usually little smell.
The colours below are common patterns, not a diagnosis.
Why does trichomoniasis cause frothy, yellow-green discharge?
Trichomoniasis is caused by a small parasite, Trichomonas vaginalis, and is one of the most common curable STIs. It classically causes frothy, yellow-green vaginal discharge with a strong odour, along with vulval soreness, itching and pain during urination or sex. Not everyone with trichomoniasis has symptoms, and up to half of infections are thought to cause no noticeable signs at all. It is easily cured with a short course of antibiotics once diagnosed, and both partners need treating together to stop reinfection.
Could it be gonorrhoea or chlamydia instead?
Gonorrhoea and chlamydia can also cause yellow or green discharge, so colour alone cannot tell them apart from trichomoniasis. Gonorrhoea discharge is often described as thicker and can occasionally be tinged yellow-green, while chlamydia discharge is usually milder and sometimes barely noticeable. Both infections are frequently symptom-free, particularly chlamydia, and both can be picked up on the same swab or urine sample. Left untreated, either can spread upwards and contribute to pelvic inflammatory disease, so testing rather than guessing from symptoms is the safer route.
What does grey, fishy-smelling discharge mean?
Grey or greyish-white discharge with a fishy smell, especially noticeable after sex, is the typical pattern of bacterial vaginosis. BV happens when the normal balance of vaginal bacteria is disrupted, allowing bacteria such as Gardnerella vaginalis to overgrow. It is not classed as a sexually transmitted infection, but it is more common in sexually active women and can be triggered by a new partner or by douching. Our Gardnerella test is a swab that identifies the bacterium so it can be treated with the right antibiotic rather than guessed at.
What does thick, white discharge mean?
Thick, white discharge that looks like cottage cheese, with intense itching and soreness, is the usual pattern of thrush (vaginal candidiasis). Thrush is caused by an overgrowth of a yeast, Candida, that normally lives harmlessly in the vagina, and it is not sexually transmitted. It can, however, look and feel similar enough to other causes of discharge that a swab is worth doing if it is a first episode or keeps coming back. Our fungal infection test checks for Candida so the right antifungal treatment can be given.
What does brown discharge mean?
Brown discharge is usually old blood that has taken longer to leave the body, most often just before or after a period. It can also follow sex, when the cervix is touched, or come from cervical ectropion, where the cells lining the cervix are more fragile and bleed easily. Less often, an infection such as chlamydia or gonorrhoea inflames the cervix and causes spotting that shows as brown. Brown discharge that keeps happening after sex, or between periods, needs a clinician to examine the cervix; our guide to brown discharge after sex covers this in more detail.
Is some discharge normal?
Yes. Clear to white discharge that changes in amount and consistency through the menstrual cycle is normal and not a sign of infection. What points towards a cause needing treatment is a change in colour towards yellow, green or grey, a new or strong smell, or discharge that comes with itching, soreness, pelvic pain or bleeding between periods. Our broader discharge guide covers how STIs affect discharge in men as well as women. If you are unsure whether what you are seeing is normal, a swab test settles it either way.
Which samples are needed?
Colour alone cannot tell the causes apart, so the clinician chooses the samples from your symptoms and the kind of sex you have had, and one visit can cover the likely causes.
What each sample is used to test for:
How testing works at our Harley Street clinic
A vaginal swab is a quick, low-discomfort sample that can be self-taken or collected by a clinician, and laboratory testing of swabs is what reliably tells trichomoniasis, gonorrhoea, chlamydia, BV and thrush apart. Our guide to private STI testing in London explains how a confidential visit works. Our standalone trichomoniasis test is £121, with results in 3 days. If you would rather have a broader check, our screening packages for women cover chlamydia, gonorrhoea, HIV and syphilis from the Bronze tier upwards, with the Gold and Platinum tiers also including trichomoniasis. You can walk in seven days a week at 117A Harley Street, and the whole visit is confidential.
If your discharge and symptoms settle after treatment but then keep recurring, our colleagues at Gynae Clinic Harley Street have written a vaginal discharge guide that covers recurrent and cyclical causes worth discussing with a gynaecologist.
Book a trichomoniasis test at 117a Harley Street: £121, results in 3 days.
References
- Vaginal discharge, NHS
- Trichomoniasis, NHS
- Bacterial vaginosis, NICE Clinical Knowledge Summaries
- Management of vaginal discharge, BASHH
- Vulvovaginal candidiasis, NICE Clinical Knowledge Summaries
