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7.4 Trichomoniasis
Identifying the cause of vaginitis symptoms enables a woman to make an informed decision about
treatment during pregnancy.
7.4.1
Background
Trichomoniasis is a common sexually transmitted vaginitis caused by the single-celled protozoan
parasite Trichomonas vaginalis. Around 70% of people with trichomoniasis do not experience symptoms
(Workowski & Berman 2010). When symptoms are present in women, they include a smelly, yellow-green
vaginal discharge with vulvar irritation (Workowski & Berman 2010). Trichomoniasis is associated with
infertility, pelvic inflammatory disease and enhanced HIV transmission (Sobel 2005; Sutton et al 2007;
Johnston & Mabey 2008; Fichorova 2009).
Prevalence of trichomoniasis in pregnancy
Trichomoniasis is the most common curable sexually transmitted infection globally, with a prevalence
among women of 8.1% (WHO 2011). Prevalence varies with age as well as geographical region.
•
Population-level data: There are no accurate national data available regarding the prevalence of
trichomoniasis in Australia and the infection is not notifiable.
•
Aboriginal and Torres Strait Islander women: Small studies of discrete populations have found an
prevalence among pregnant women of 15.5–17.6% (Josif et al 2012) in remote areas and 7.2% in an
urban area (Panaretto et al 2006).
•
Country of origin: Prevalence in the United States is in the range of 3–3.7% (French et al 2006; Sutton et
al 2007; Mann et al 2009), higher among African American women (10–14%) (Caliendo et al 2005; Miller
et al 2005; French et al 2006) and slightly lower among adolescent women (2.8%)(Miller et al 2005).
Prevalence in other regions has been estimated as 0.3–6% among South American women (Lobo et
al 2003; Gondo et al 2010), 5.5–8.5% among Asian women (Sami & Baloch 2005; Azargoon & Darvishzadeh
2006; Madhivanan et al 2009) and 5.4–17.6% among African women (Adu-Sarkodie 2004; Stringer et al
2010).
•
Risk factors: Risk factors include multiple sexual partners, previous sexually transmitted infections,
non-use of barrier contraceptives, work in the sex industry, intravenous drug use, smoking, low
socioeconomic status and incarceration (Brown 2004; Say & Jacyntho 2005; Johnston & Mabey 2008;
Workowski & Berman 2010).
Risks associated with trichomoniasis in pregnancy
•
Pregnancy risks: Trichomoniasis in pregnancy is associated with increased risk of preterm birth and
low birth weight (Buchmayer et al 2003; Mann et al 2009; Gülmezoglu & Azhar 2011).
•
Risks to the baby: Maternal trichomoniasis has been associated with genital and respiratory
infections of the newborn (Carter & Whithaus 2008; Trintis et al 2010).
7.4.2
Screening for trichomoniasis
Summary of the evidence
In the United States (Workowski & Berman 2010), testing for trichomoniasis during pregnancy is only
recommended for women with symptoms. Recommendations on screening have not previously been
developed in the United Kingdom or Australia.
Specimen collection
Small low-level studies in non-pregnant populations have concluded that:
•
self-collected vaginal swabs correlate with specimens collected by health professionals (Smith et al
2005; Kashyap et al 2008; Huppert et al 2010) and are easy to perform (Kashyap et al 2008); and
CONSULTATION DRAFT
•
self-collection by tampon sampling is acceptable to women (van de Wijgert et al 2006), is easily
incorporated into practice and may be suitable in remote settings as samples do not require
refrigeration (Garland & Tabrizi 2004).
Diagnostic test accuracy
A range of testing methods for trichomoniasis is used in Australia; the most appropriate test will depend
on the clinical setting.
•
Polymerase chain reaction (PCR) testing of vaginal swabs has high sensitivity (96–100%) and
specificity (97–100%) (Lobo et al 2003; Caliendo et al 2005; Smith et al 2005; Pillay et al 2007). Small studies
have found that PCR testing of tampon samples has high sensitivity (94–100%) (Knox et al 2002; Sturm
et al 2004). PCR testing of urine samples has lower sensitivity and specificity (76.7% and 97%) (Pillay et
al 2007).
•
Culture testing of vaginal swabs has high sensitivity (63.0–98.2%) and specificity (99.4–100%) (Lobo et
al 2003; Adu-Sarkodie 2004; Caliendo et al 2005; Smith et al 2005). It requires an incubator and culture
medium, and may take up to 7 days for a result.
•
Wet mount microscopy has low sensitivity (43.6–81.5%) but a high specificity (93–100%) (Lara-Torre &
Pinkerton 2003; Lobo et al 2003; Adu-Sarkodie 2004; Smith et al 2005; Pillay et al 2007). Accurate diagnosis
depends on immediate evaluation of a moist specimen and the skill of the examiner (Hollier &
Workowski 2005).
•
Pap smear is not adequate as the sole method of diagnosis of trichomoniasis because of its low
sensitivity (60.7–72.1%) and the delay in obtaining results (Lara-Torre & Pinkerton 2003; Lobo et al 2003;
Smith et al 2005).
There is insufficient evidence to assess the accuracy of the latex agglutination kit in diagnosing
trichomoniasis (Adu-Sarkodie 2004).
Benefits and harms of screening
While accurate diagnostic tests are available, the benefits of screening are limited by uncertainties
about the effect of treatments during pregnancy. Advantages of identifying and treating
trichomoniasis include relief of symptoms, reduced risk of further transmission and possible prevention of
genital and respiratory infections in the newborn (Workowski & Berman 2010). Potential harms of screening
include false positive diagnosis (Johnson et al 2007) and adverse effects associated with treatment (see
below).
In areas of high prevalence, all women should be screened for trichomoniasis as part of regular
women’s health screening. It is preferable that woman be tested either before or after the pregnancy,
to avoid adverse effects of treatment.
Recommendation 14
Grade B
Offer testing to women who have symptoms of trichomoniasis, but not to asymptomatic women, during
pregnancy.
Availability of safe and effective treatments for trichomoniasis
Metronidazole and tinidazole are used to treat trichomoniasis (Owen & Clenney 2004; Fung & Doan 2005;
Wendel & Workowski 2007; Workowski & Berman 2010). The Therapeutic Goods Administration classifies
metronidazole as pregnancy category B2 and tinidazole as B3.
Based on the limited evidence available, treatment with metronidazole provides parasitological cure in
around 90% of women and would likely be more effective if partners were also treated (Workowski &
Berman 2010; Gülmezoglu & Azhar 2011). However, it does not reduce risk of preterm birth or low birth
weight in asymptomatic women (Gülmezoglu & Azhar 2011) and may increase the risk of preterm birth
(Carey & Klebanoff 2003; Hay & Czeizel 2007).
Studies into the effect of treatment in women with symptomatic trichomoniasis are also limited and
findings are inconsistent. Some suggest an increased incidence of preterm birth (Riggs & Klebanoff 2004;
CONSULTATION DRAFT
Okun et al 2005) and others found no association with preterm birth (Mann et al 2009). Findings may be
affected by method of assessing gestational age (Stringer et al 2010) and timing of diagnosis.
Due to the lack of clarity on the risk of preterm birth, treatment of asymptomatic pregnant women is not
recommended but may be a consideration after 37 weeks gestation. Treatment for women with
symptoms requires consideration of the risks and benefits for the individual woman.
Repeat screening
Due to the high rates of reinfection among women diagnosed with trichomoniasis, rescreening 3
months following treatment may be a consideration, although this approach has not been evaluated
(Workowski & Berman 2010).
7.4.3
Discussing trichomoniasis
Discussion to inform a woman’s decision-making about trichomoniasis screening should take place
before testing takes place and include:
•
it is the woman’s choice whether she has the test or not;
•
trichomonisasis is a common sexually transmitted infection and most people do not experience
symptoms;
•
trichomoniasis is associated with increased risk of preterm birth and low birth weight and may
cause some types of infection in the newborn;
•
treatment of trichomoniasis relieves symptoms, reduces the risk of transmission and may prevent
related infections in the newborn but may not reduce the risk of preterm birth;
•
testing and treatment of partners is advisable if infection is identified and the couple should abstain
from sex until treatment is complete and symptoms have resolved; and
•
testing for other sexually transmitted infections may be needed.
7.4.4
Practice summary: trichomoniasis
When: A woman has signs or symptoms of vaginitis.
Who: Midwife; GP; obstetrician; Aboriginal and Torres Strait Islander Health Practitioner; Aboriginal and
Torres Strait Islander Health Worker; multicultural health worker, sexual health worker.
Discuss the reasons for testing for trichomoniasis: Explain that testing is necessary to identify the cause
of the symptoms.
Take a holistic approach: If a woman is found to have trichomoniasis, other considerations include
counselling, contact tracing, partner testing and treatment and testing for other sexually
transmitted infections.
Document and follow-up: If a woman is tested for trichomoniasis, tell her the results and note them in
her antenatal record. Have a system in place so that women’s decisions about treatment are
documented and women who test positive for trichomoniasis during pregnancy are given
ongoing follow-up and information.
7.4.5
Resources
Sexually transmitted infections (STIs) in pregnancy. In: Minymaku Kutju Tjukurpa Women’s Business Manual, 4th
edition. Congress Alukura, Nganampa Health Council Inc and Centre for Remote Health.
http://www.remotephcmanuals.com.au
Workowski KA & Berman S (2010) Sexually transmitted diseases treatment guidelines, 2010. MMWR Recomm Rep
59(RR-12): 1–110.
7.4.6
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