Trichomoniasis
NICE CKS Trichomoniasis. Last revised: Dec 2024.
Background Information
Aetiology
Trichomoniasis is an STI caused by the flagellate protozoan Trichomonas vaginalis.
In adults, transmission is almost exclusively through sexual intercourse.
Risk factors include:
- Current gonorrhoea or chlamydia infection (in women)
- 2 or more sexul partner in the previous year
- Lack of consistent condom use
- Women with bacterial vaginosis
Epidemiology
Trichomoniasis is the most common non-viral STI in the world.
However, it is relatively rare in the UK.
Trichomoniasis is ~4x more common in women than men. [Ref]
Clinical Features
Up to 50% of women with trichomoniasis are asymptomatic
If symptomatic (women):
- Offensive vaginal discharge with fishy odour
- Classic yellow-green and frothy discharge (but only seen in 10-30% cases)
- Vaginal discharge varies in consistency from thin and scanty to profuse and thick
- Dysuria
- Signs of vulval inflammation (e.g. irritation, itching, soreness)
In men: urethral discharge and/or dysuria
Trichomoniasis is associated with signs of inflammation e.g. irritation, itching, or soreness. However, this is typically absent in bacterial vaginosis.
Both trichomoniasis and bacterial vaginosis cause offensive fishy-smelling vaginal discharge
- Discharge in bacterial vaginosis is typically thin, white, and homogeneous
- Discharge in trichomoniasis is classically yellow-green and frothy (but could also vary in consistency)
Complications
In Women
Pregnancy-associated complications:
- Preterm delivery
- Low birth weight infant
- Maternal postpartum sepsis
- Infertility
Trichomoniasis increases risk of:
- Bacterial vaginosis (due to altered normal vaginal flora)
- PID
- Cervical cancer
- HIV transmission
In Men
- Facilitation of HIV transmission
- Infertility
- Acute and chronic prostatitis
- Increased risk of prostate cancer
Diagnosis
Women
| Examination / investigation | Findings in trichomoniasis |
|---|---|
| Speculum examination |
|
| pH testing of vaginal discharge | pH >4.5 is suggestive of trichomoniasis
Note that pH >4.5 is also seen in bacterial vaginosis. While normal pH (3.5-4.5) is seen in vaginal candidiasis. |
| High vaginal swab from the posterior fornix | NAAT to detect Trichomonas vaginalis DNA (preferred 1st line test)
Microscopy (wet mount) – allows point-of-care testing
|
Men
Take a urethral swab sample or arrange a self-taken penile-meatal swab for NAAT
Other Tests
For both women and men with suspected trichomoniasis, offer testing for:
- Chlamydia
- Gonorrhoea
- HIV
- Syphilis
- Hepatitis (if the patient is at high risk)
Management
Ideally, treatment of confirmed trichomoniasis should be provided by a GUM clinic or other local specialist sexual health service.
General Advice / Conservative Management
Advise sexual abstinence for at least 1 week after starting treatment and until the person and partner(s) have completed treatment and follow-up.
Pharmacological Management
1st line: oral metronidazole 400-500 mg BD for 7 days
Alternative: metronidazole 2g single oral dose
Management in Pregnant/Breastfeeding Individuals
Similar to treatment in non-pregnant individuals:
- 1st line: oral metronidazole 400mg BD for 5-7 days
- If patient is asympotmatic (and pregnant), seek specialist advice
Avoid oral metronidazole 2g single dose in pregnancy/breastfeeding.
Follow Up
Tests of cure are only recommended if the patient remains symptomatic following treatment, or if symptoms recur.
Partner Testing and Management
The following partners should be offered treatment (see pharmacological management section)
- Current partner(s), and
- ANY partner(s) from 4-weeks prior to presentation