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Pregnancy Care Guidelines

42 Trichomoniasis

Identifying the cause of vaginitis symptoms enables a woman to make an informed decision about treatment during pregnancy.

42.1 Background

Trichomoniasis is a 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 vulval 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).

42.1.1 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 data available regarding the national prevalence of trichomoniasis in Australia and the infection is not notifiable.
  • Geographical location: The reported prevalence of trichomoniasis in different regions of Australia is extremely variable, ranging from virtually zero in the largest cities (Marrone et al 2008; Lusk et al 2010; Uddin et al 2011) to 25% in remote northern Aboriginal communities (Guy et al 2011). A study of prevalence in rural and remote New South Wales found that prevalence increased with remoteness in both Aboriginal and non- Indigenous women (Ryder et al 2012).
  • 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 has been estimated as 3–3.7% among women in the United States (French et al 2006; Sutton et al 2007; Mann et al 2009), 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), 10–14% among African American women (Caliendo et al 2005; Miller et al 2005; French et al 2006) 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).

42.1.2 Risks associated with trichomoniasis in pregnancy

  • Pregnancy risks: Trichomoniasis in pregnancy may be 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).

42.2 Testing for trichomoniasis

In the United States (Workowski & Berman 2010), testing for trichomoniasis during pregnancy is only recommended for women with symptoms. Recommendations on testing during pregnancy have not previously been developed in the United Kingdom or Australia.

42.2.1 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)
  • 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 refrigeration is not required (Garland & Tabrizi 2004).

42.2.2 Diagnostic test accuracy

Testing for trichomoniasis in Australia is mostly carried out using PCR, which is rapidly replacing culture testing as it has higher sensitivity and results are available more quickly.

  • 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 a sensitivity of 63.0–98.2% and specificity of 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.

While trichomoniasis is occasionally diagnosed by Pap smear, its use is not adequate as the sole method of diagnosis 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).

42.2.3 Benefits and harms of testing

While accurate diagnostic tests are available, the benefits of testing 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 testing include false positive diagnosis (Johnson et al 2007) and adverse effects associated with treatment (see below).

Recommendation

  • Grade B
  • 48

Offer testing to women who have symptoms of trichomoniasis, but not to asymptomatic women. 

Approved by NHMRC in June 2014; expires June 2019

42.2.4 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; 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.

42.2.5 Repeat testing

Due to the high rates of reinfection among women diagnosed with trichomoniasis, retesting 3 months following treatment may be a consideration, although this approach has not been evaluated (Workowski & Berman 2010).

42.3 Discussing trichomoniasis

Discussion to inform a woman’s decision-making should take place before testing takes place and include:

  • trichomoniasis is a 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
  • testing for other sexually transmitted infections may be needed.

42.4 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.

What

  • 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. 

42.5 Resources

References

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  • Azargoon A & Darvishzadeh S (2006) Association of bacterial vaginosis, trichomonas vaginalis, and vaginal acidity with outcome of pregnancy. Arch Iran Med 9(3): 213–17.
  • Brown D, Jr. (2004) Clinical variability of bacterial vaginosis and trichomoniasis. J Reprod Med 49(10): 781–86.
  • Buchmayer S, Sparen P, Cnattingius S (2003) Signs of infection in Pap smears and risk of adverse pregnancy outcome. Paediatr Perinat Epidemiol 17(4): 340–46.
  • Caliendo AM, Jordan JA, Green AM et al (2005) Real-time PCR improves detection of Trichomonas vaginalis infection compared with culture using self-collected vaginal swabs. Infect Dis Obstet Gynecol 13(3): 145–50.
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  • Fichorova RN (2009) Impact of T. vaginalis infection on innate immune responses and reproductive outcome. J Reprod Immunol 83(1-2): 185–89.
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  • Okun N, Gronau KA, Hannah ME (2005) Antibiotics for bacterial vaginosis or Trichomonas vaginalis in pregnancy: a systematic review. Obstet Gynecol 105(4): 857–68.
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  • Panaretto KS, Lee HM, Mitchell MR et al (2006) Prevalence of sexually transmitted infections in pregnant urban Aboriginal and Torres Strait Islander women in northern Australia. Aust N Z J Obstet Gynaecol 46(3): 217–24.
  • Pillay A, Radebe F, Fehler G et al (2007) Comparison of a TaqMan-based real-time polymerase chain reaction with conventional tests for the detection of Trichomonas vaginalis. Sex Transm Infect 83(2): 126–29.
  • Riggs MA & Klebanoff MA (2004) Treatment of vaginal infections to prevent preterm birth: a meta-analysis. Clin Obstet Gynecol 47(4): 796–807; discussion 81–82.
  • Ryder N, Woods H, McKay K et al (2012) Trichomonas vaginalis prevalence increases with remoteness in rural and remote New South Wales, Australia. Sex Transm Dis 39(12): 938-41.
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  • Stringer E, Read JS, Hoffman I et al (2010) Treatment of trichomoniasis in pregnancy in sub-Saharan Africa does not appear to be associated with low birth weight or preterm birth. S Afr Med J 100(1): 58–64.
  • Sturm PD, Connolly C, Khan N et al (2004) Vaginal tampons as specimen collection device for the molecular diagnosis of non-ulcerative sexually transmitted infections in antenatal clinic attendees. Int J STD AIDS 15(2): 94–98.
  • Sutton M, Sternberg M, Koumans EH et al (2007) The prevalence of Trichomonas vaginalis infection among reproductive-age women in the United States, 2001-2004. Clin Infect Dis 45(10): 1319–26.
  • Trintis J, Epie N, Boss R et al (2010) Neonatal Trichomonas vaginalis infection: a case report and review of literature. Int J STD AIDS 21(8): 606–07.
  • Uddin RN, Ryder N, McNulty AM et al (2011) Trichomonas vaginalis infection among women in a low prevalence setting. Sex Health 8(1): 65-8.
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Last updated: 
20 November 2018