Vaginal trichomoniasis: Clinical sciences

Vaginal trichomoniasis is among the most prevalent sexually transmitted infections, or STIs, worldwide. It is caused by the protozoan parasite, Trichomonas vaginalis. Most patients infected with trichomonas have minimal or no symptoms, and untreated infections can last for months to years. Trichomonas infection is associated with an increased risk of both HIV acquisition and HIV shedding, and it increases the risk of pelvic inflammatory disease among HIV-positive patients. Additionally, it has been associated with an increased risk of cervical cancer. In pregnancy, trichomonas infection increases the risk of preterm birth, prelabor rupture of membranes and small for gestational age infants.

Your first step in evaluating a patient who presents with a chief concern suggesting vaginal trichomoniasis is obtaining a focused history and physical exam. This should include a sexual history, such as recent sexual activity or new partners, so be sure to have a private and confidential discussion. Although it might be difficult, you should ask caregivers of young patients to step out of the room for this discussion. Additionally, always consider sexual assault or abuse whenever a young patient has a positive sexual activity history, especially if the patient is a child. If there is abuse going on, you will need to follow up with allegations of abuse in accordance with your State’s law.

Now, keep in mind that trichomoniasis can be spread through vaginal fluids So some practices like sharing of sex toys can cause infection. In addition to sexual history, ask about hygiene practices, such as douching, which can remove some of the bacteria that make up the normal vaginal flora, increasing the risk of overgrowth of infectious pathogens. Although most patients are usually asymptomatic, some may report a malodorous vaginal discharge, vulvar pruritus or irritation, and dysuria.

Physical exam findings include a yellow frothy vaginal discharge; as well as vaginal or cervical erythema with petechiae, which is often referred to as a “strawberry cervix.” Based on these findings, you should suspect vaginal trichomoniasis.

Here is a high-yield fact! In the United States, the prevalence of vaginal trichomoniasis is almost 10 times higher among black patients than non-Hispanic white patients. Some additional risk factors for trichomonas infection include socioeconomic factors like incarceration, having less than a high school education, and poverty.

So, if you suspect vaginal trichomoniasis, let’s take a look at your next step to confirm the diagnosis. To do this, obtain samples of the vaginal discharge from the vaginal walls and fornices. Evaluate the discharge with saline microscopy, particularly looking for motile trichomonads, and assess the vaginal pH. In addition, you may perform nucleic acid amplification testing, or NAAT, for Trichomonas vaginalis. While NAAT testing is highly sensitive and detects more trichomonas infections, keep in mind that it’s more expensive and less timely than microscopy.

Okay, time for a couple of clinical pearls! First, vaginal cultures can be used to detect Trichomonas vaginalis, but these are rarely used, as NAAT testing has higher sensitivity and better detection rates. Additionally, there are also some FDA-approved rapid tests available for detecting Trichomonas vaginalis. Second, vaginal trichomoniasis has a high prevalence in patients with HIV infection, can increase viral shedding, and is strongly associated with pelvic inflammatory disease among these patients. For these reasons, yearly screening for trichomonas is recommended for patients with HIV infection.

Now let’s review our results. If there is an absence of trichomonads on saline microscopy, the vaginal pH is lower than or equal to 4.5, or a NAAT is negative for Trichomonas, consider an alternative diagnosis. However, keep in mind that time matters here, and sensitivity decreases quickly within 1 hour after specimen collection, so you should attempt to evaluate it immediately!