Merck Manual

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Trichomonal Vaginitis

By

Oluwatosin Goje

, MD, MSCR, Cleveland Clinic, Lerner College of Medicine of Case Western Reserve University

Reviewed/Revised Mar 2023
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Trichomonal vaginitis is a vaginal infection caused by the protozoa Trichomonas vaginalis.

  • Trichomonal vaginitis is usually sexually transmitted.

  • It can cause a green or yellow discharge, which may be profuse, smell fishy, and be accompanied by itching or irritation.

  • If symptoms suggest a vaginal infection, doctors examine a sample of the discharge and/or fluid from the cervix and test it for infectious organisms that can cause infection.

  • Always using a condom during sexual activity can help prevent this infection.

  • Treatment is with metronidazole or tinidazole.

Protozoa are a type of parasite. The protozoa Trichomonas vaginalis can cause symptoms soon after they enter the vagina, or the protozoa can remain in the vagina or on the cervix (the lower part of the uterus that opens into the vagina) for weeks or months without causing any symptoms. The bladder may also be infected. In men, the protozoa usually cause no symptoms and may remain in the urinary tract for a few days or weeks without causing symptoms. Thus, women and men may be unaware that they are infecting their sex partners.

Causes of Trichomonal Vaginitis

Genital infections with Trichomonas (trichomoniasis Trichomoniasis Trichomoniasis is a sexually transmitted infection of the vagina or urethra that is caused by the protozoa Trichomonas vaginalis and that causes vaginal irritation and discharge and sometimes... read more ) are almost always sexually transmitted. Women can be infected through sexual contact with men or women. But men can be infected through sexual contact only with women, not with men. Many people who have this infection also have gonorrhea Gonorrhea Gonorrhea is a sexually transmitted infection caused by the bacteria Neisseria gonorrhoeae, which infect the lining of the urethra, cervix, rectum, or throat, or the membranes that cover... read more Gonorrhea or another sexually transmitted infection.

Because the protozoa can remain in women for a long time without causing symptoms, determining when the infection was acquired and thus from whom can be difficult or impossible.

Symptoms of Trichomonal Vaginitis

Women with trichomonal vaginitis may have a green or yellow vaginal discharge that is sometimes frothy, profuse, or both. It may smell fishy. The genital area may itch, and the vagina may be red and tender (irritated). As a result, sexual intercourse may be painful. Urination may also be painful if the bladder becomes infected.

Diagnosis of Trichomonal Vaginitis

  • A doctor's evaluation

  • Examination of a sample of the discharge and/or fluid from the cervix

If girls or women have a vaginal discharge that is unusual or that lasts for more than a few days or have other vaginal symptoms, they should see a doctor.

Doctors suspect trichomonal vaginitis based on symptoms, such as a green or yellow frothy discharge. They then ask questions about the discharge, other symptoms, and possible causes (such as sexually transmitted infections).

To confirm the diagnosis, doctors do a pelvic examination Gynecologic Examination For gynecologic care, a woman should choose a health care practitioner with whom she can comfortably discuss sensitive topics, such as sex, birth control, pregnancy, and problems related to... read more . While examining the vagina, the doctor takes a sample of the discharge with a cotton-tipped swab. The sample is examined under a microscope. With information from this examination, the doctor can often identify the cause of the symptoms.

Usually, the doctor also uses a swab to take a sample of fluid from the cervix to test for other sexually transmitted infections.

If children have trichomonal vaginitis, doctors evaluate them to determine whether sexual abuse could be the cause.

Treatment of Trichomonal Vaginitis

  • Metronidazole or tinidazole

Women with trichomonal vaginitis should be treated with metronidazole given by mouth. Sex partners should be treated at the same time. An alternative treatment is tinidazole taken by mouth.

During sexual intercourse, condoms should be used until the infection resolves to help prevent transmission of the infection.

Prevention of Trichomonal Vaginitis

Always using a condom Condoms Barrier contraceptives physically block the sperm’s access to a woman’s uterus. They include condoms, diaphragms, cervical caps, contraceptive gels, contraceptive sponges, and spermicides (foams... read more Condoms correctly during oral, anal, and genital sex can help prevent this infection from being transmitted. However, Trichomonas vaginalis protozoa can infect areas that are not covered by a condom. So condoms do not fully protect people from being infected.

The following general measures can also help prevent trichomonal vaginitis:

  • Decreased risk of exposure to STIs by using safer sex practices (limiting the number of sex partners, not having high-risk sex partners [people with many sex partners or who do not practice safer sex]) or practicing mutual monogamy or abstinence

  • Prompt diagnosis and treatment of the infection (to prevent spread to other people)

  • Identification of the sexual contacts of infected people, followed by counseling or treatment of these contacts

Drugs Mentioned In This Article

Generic Name Select Brand Names
Flagyl, Flagyl ER, Flagyl RTU, LIKMEZ, MetroCream, MetroGel, MetroGel Vaginal, MetroLotion, Noritate, NUVESSA, Nydamax, Rosadan, Rozex, Vandazole, Vitazol
Tindamax
NOTE: This is the Consumer Version. DOCTORS: VIEW PROFESSIONAL VERSION
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