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A missed diagnosis of trichomoniasis

Rosenberger, Kelly D. DNP, CNM, WHNP-BC; Fisk, Courtney BSN

doi: 10.1097/01.NPR.0000511777.44250.20
Online exclusive: Clinical Case Report

Kelly D. Rosenberger is a clinical assistant professor and director of the College of Nursing Rockford Regional Campus, University of Illinois at Chicago, College of Nursing, Rockford, Ill. as well as a certified nurse midwife and women's health NP at the University of Illinois at Chicago, College of Medicine, Rockford, Ill.

Courtney Fisk is a women's health DNP student at the University of Illinois at Chicago, Rockford Regional Campus, Rockford, Ill.

The authors have disclosed that they have no financial relationships related to this article.

Mrs. H is a healthy 48-year-old with complaints of intermittent, recurrent mild dysuria, white vaginal discharge without odor, and mild vaginal itching with irritation for the past 3 months. She reports her last sexual encounter was 3 months ago with her spouse who travels for work and has not been home since. She reports using numerous over-the-counter (OTC) vaginal yeast preparations and has visited her local immediate care clinic twice in the past 3 months.

Mrs. H was tested for urinary tract infections twice; however, when she called the clinic regarding her cultures, she was informed of negative urine culture results. In frustration, after completing another OTC yeast treatment, Mrs. H presented to her NP's office seeking treatment for the above symptoms and denied any other complaints.

Mrs. H's vital signs were stable. Physical exam was unremarkable with the exception of creamy white vaginal discharge during a vaginal exam, a friable cervix covered with white discharge, and several small punctate lesions. She denied uterine, adnexal, suprapubic, or cervical motion tenderness on bimanual palpation of the pelvis. The pH of the vaginal secretions/discharge was 5.0, and a urinalysis dipstick revealed moderate leukocytes and trace hematuria.

Cultures were obtained for gonorrhea and chlamydia; potassium hydroxide (KOH) and wet mount preparations were obtained for microscopic analysis while Mrs. H was still in the office. The KOH microscopic analysis was negative for fungal elements, while the wet mount revealed numerous motile trichomonads with flagella, mixed flora, increased polymorphonuclear leukocytes, and clue cells partially obscured by the remnants of the OTC yeast preparation used by Mrs. H 2 days prior to the appointment.

Upon further questioning, Mrs. H reported that she did not have a vaginal exam during her two prior appointments in the immediate care clinic and only provided a urine specimen at those visits.

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Epidemiology, prevalence, and etiology

Trichomoniasis is the most common curable sexually transmitted infection, with an estimated 248 million new cases annually worldwide; the United States accounts for 3.7 million cases.1,2 Because trichomoniasis is not nationally reportable and many cases may be asymptomatic, precise statistics are difficult to obtain. Based on the 2001 to 2004 National Health and Nutrition Examination Survey, the prevalence of trichomoniasis was 3.1% in women ages 14 to 49 in the United States.3

Comparing prevalence by race, non-Hispanic Black women have a higher prevalence of trichomoniasis (13.1%) than non-Hispanic White women (1.3%) and Mexican American women (1.8%).4 High-risk groups such as prison inmates, drug users, and sex workers also have a higher prevalence. In women clinically presenting with vaginal complaints, 18% to 50% have trichomoniasis. Those infected with trichomoniasis increase transmission of HIV twofold.5

Other factors that may increase susceptibility to trichomoniasis include lack of condom use, increased number of lifetime sex partners, lack of healthcare access, douching, and poverty.6 Women engaging in high-risk sexual activity with new or multiple partners are at greater risk of infection.

Trichomoniasis is caused by the motile unicellular parasitic protozoan Trichomonas vaginalis. Transmission of trichomoniasis is primarily via sexual activity among humans (the only known host).

T. vaginalis is approximately the size of a white blood cell; its dimensions may vary with physical conditions.7 T. vaginalis is about 10 micrometers (um) to 20 um long and 2 to 14 um wide and has 4 flagella protruding from the anterior cell wall and 1 flagellum extending from the middle of the organism with an axostyle extending from the posterior cell wall.8 The lifecycle of T. vaginalis has a parasite residing in the lower female genital tract and in the male urethra and prostate, where it replicates via binary fission.9 This parasite does not survive well in the external environment.

Due to the high prevalence of trichomoniasis, testing should be done routinely in women seeking care for complaints of vaginal discharge and/or vulvovaginal itching and irritation. In the case of Mrs. H, a vaginal exam with screening for trichomoniasis at her first visit to the immediate care clinic could have provided assessment, diagnosis, and treatment in a timely manner.

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Clinical manifestations

The leading signs and symptoms of acute trichomoniasis include a purulent, malodorous, thin vaginal discharge often associated with dysuria, pruritus, urinary frequency, lower abdominal pain, dyspareunia, and possible postcoital bleeding. Women often note that the signs and symptoms are worse during menstruation; however, trichomoniasis can range from an asymptomatic state to a critical pelvic inflammatory disease. Because infection can persist in the asymptomatic carrier state in as many as 50% of infected women, it is difficult to ascertain when and from whom it was acquired, leading to high transmission rates.10



Typically, the vaginal exam reveals vulvar and vaginal mucosal erythema. In 10% to 30% of symptomatic women, the classic yellow-green, frothy, malodorous discharge is present and small punctate hemorrhages (known as strawberry cervix) may be visible on the cervix in 2% of cases.11 (See Strawberry cervix.)12 Differential diagnoses for vaginal trichomoniasis include physiologic leukorrhea, bacterial vaginitis, and vaginal candidiasis (see Diagnostic clues for vaginal infections).13

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Diagnostic testing

The vaginal wet mount, also known as a vaginal smear or wet prep, is an inexpensive test done using a speculum, sterile cotton swabs, microscope slides, and a compound microscope. While its specificity is estimated at 51% to 65%, the sensitivity varies from 50% to 80% for diagnosing trichomoniasis on microscopy.4,14 After positioning the patient in the lithotomy position on the exam table with the speculum properly inserted, a sterile cotton swab is used to collect a sample of the vaginal discharge from the cervix, mucosa of the posterior vagina, and vaginal wall.

When preparing the saline prep slide, it is important to remember to not let the specimen dry on either the swab or slide. Using what is known as the “direct method,” the vaginal discharge from the swab may be directly applied to the slide (only a small portion is needed).6 Afterward, one drop of saline is added to the specimen on the slide and a coverslip is applied.

Other indirect methods may be used for the saline prep slide, such as placing the swab in a small test tube of 0.9% sodium chloride to be used for slide preparation later or placing the drop of saline first on the slide, then gently rolling the swab with the secretions in the saline and applying the coverslip. Regardless of technique, the specimen should be viewed microscopically immediately following collection and preparation.6 (See Six simple steps for office microscopy.) Additionally, to rule out bacterial vaginosis, the amine “whiff” test may be easily obtained while preparing the KOH slide for microscopic review of fungal elements.

With saline wet preparations approximately 50% to 80% sensitive to trichomoniasis, another diagnostic option may play a role in detection.14 Considered to be the gold standard for trichomoniasis diagnosis, cultures have a specificity approaching 100%, but sensitivity can range between 75% and 96% and are not widely used due to poor transport viability of specimens, increased cost, and time to results.4 Collecting the specimen for culture is performed in a similar fashion using a sterile cotton swab to obtain vaginal discharge. After being placed in the culture medium, the specimen is then sent to a lab, taking generally 24 to 120 hours for results.4

Table Dia

Table Dia

Additional diagnostic tools include the use of pH paper to assess vaginal pH. The normal vaginal pH ranges from 3.8 to 4.5; secretions with trichomoniasis are greater than 4.5.13,15 However, diagnosis of trichomoniasis solely based on vaginal pH is not possible due to other vaginal infections having effects on the vaginal pH.

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Management of trichomoniasis

Numerous studies have demonstrated that trichomoniasis has been associated with a range of adverse clinical outcomes, including preterm birth, vaginal cuff abscess or cellulitis post hysterectomy, pelvic inflammatory disease, and infertility.14,16 Trichomoniasis also increases susceptibility to HIV acquisition twofold in women.5 Thus, treatment is indicated for asymptomatic and symptomatic women as well as their partners.

Uncomplicated trichomoniasis should be treated with metronidazole or tinidazole. Curative therapy of trichomoniasis is only provided by this class of medications.2 First-line therapy for trichomoniasis includes a single 2 g oral dose of either metronidazole or tinidazole, with cure rates of 90% to 95% reported in randomized trials.2,17 Metronidazole 500 mg orally twice a day for 7 days is an alternative to the single-dose regimen and is the recommended treatment regimen by the CDC for HIV-infected women.2,18,19 For symptomatic pregnant women, the CDC advises the single 2 g metronidazole oral dose given during any trimester, and tinidazole is to be avoided during pregnancy.2,18,19

During treatment with metronidazole or tinidazole, advise patients to abstain from alcohol use for 24 hours after completion of metronidazole or 72 hours after completion of tinidazole. Patients should also be advised to avoid intercourse until 7 days after all partners have completed the last antibiotic dose.

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Case study revisited

Mrs. H was initially treated with metronidazole, 2 g orally, in a single dose, and her spouse was offered a prescription per the expedited partner therapy guidelines.2,20 Mrs. H's spouse decided not to complete the treatment because he had no symptoms. Mrs. H returned to the clinic a month later with the same symptoms due to reinfection; she was given a longer course of metronidazole 500 mg orally twice daily for 7 days, and she was again advised that her spouse needed treatment.

Mrs. H replied she was no longer sexually active and was not living with her spouse so she was not concerned about reinfection. Mrs. H reported mild relief of symptoms after the second course of antibiotic treatment and returned to the clinic 6 weeks later with the same symptoms, reporting that she had not been sexually active since before the second course of therapy. Based on the 2015 CDC guidelines for refractory cases, Ms. H was given a regimen of tinidazole 2 g orally in divided doses for 7 days.2

As recently noted in clinics in six cities across the United States, metronidazole resistance has been reported in 4% of women with trichomoniasis.21 The final regimen cured Mrs. H upon assessment when she returned 4 weeks later to the clinic symptom-free with normal vaginal and microscopic exams. If this regimen failed, susceptibility testing would have been the next step.2

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Importance of the vaginal exam

This case highlights the importance of the vaginal exam when evaluating a patient for complaint of vaginal discharge and/or vulvovaginal itching and irritation. In many cases, the vaginal exam, along with in-office testing with the amine “whiff” test, vaginal pH, and microscopy, will reveal the etiology of the patient's complaints. The vaginal exam is not only essential for accurate diagnosis and proper treatment; in this case, it would have led to cost savings related to repeated office visits and the inappropriate use of OTC products. Additionally, the vaginal exam at the first office visit would have avoided the delay in the diagnosis of trichomoniasis.

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Six simple steps for office microscopy6

  • Place the slide on the microscope stage for exam over the beam of light.
  • Use the coarse focus, low light, and 10x objective lens to bring the slide into focus.
  • Move the slide to scan the entire saline preparation, using the fine focus to view clearly.
  • Use the 10x objective lens, adjust the lighting, and refocus to identify structures, such as yeast buds, pseudohyphae, clue cells, trichomonads (observe for movement) and change to the 40x objective lens to identify structures or artifacts (hair, fiber, bubbles, or rod bacteria) for diagnosis.
  • Using an “S” pattern, view the slide in at least 10 fields to confirm structure identity.
  • Note and record findings.
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