The advanced practice registered nurse (APRN) assesses an 18 year-old patient who reports 2 months of foul-smelling, profuse, yellowish-green vaginal discharge. There is also itching and burning during urination. Visualization of the vulva shows minor erythema. The vaginal mucosa is diffusely erythematous. Bimanual examination is unremarkable. What diagnosis is most likely?

Trichomonal vaginitis is a sexually transmitted infection caused by Trichomonas vaginalis, a protozoan parasite affecting the lower genital tract. It commonly presents with profuse, foul-smelling, yellow-green vaginal discharge accompanied by vulvar irritation, itching, dysuria, and vaginal erythema. The vaginal mucosa may appear diffusely inflamed, and the cervix can sometimes show a “strawberry” appearance due to punctate hemorrhages. Recognizing the characteristic discharge and associated irritation helps distinguish it from other causes of vaginitis. Rationale: A. Atrophic vaginitis is usually seen in postmenopausal women due to decreased estrogen levels causing thinning and dryness of the vaginal mucosa. Symptoms commonly include vaginal dryness, dyspareunia, and irritation rather than profuse yellow-green discharge. It would be very unlikely in an 18-year-old patient with this presentation. B. Trichomonal vaginitis is characterized by frothy, profuse, foul-smelling yellow-green discharge with associated itching, burning, dysuria, and diffuse vaginal erythema. The infection causes inflammation of the vaginal mucosa and vulva, leading to irritation and discomfort. This presentation matches the symptoms described, making it the most likely diagnosis. C. Candidal vaginitis typically presents with thick, white, “cottage cheese-like” discharge rather than yellow-green discharge. Intense itching and vulvar irritation are common, but the odor is usually minimal or absent. The profuse malodorous discharge is more consistent with trichomoniasis than candidiasis. D. Bacterial vaginosis usually causes a thin, grayish-white vaginal discharge with a strong fishy odor, especially after intercourse. It does not cause significant vulvar itching, dysuria, or marked vaginal erythema because inflammation is minimal. The presence of yellow-green discharge and diffuse erythema makes trichomonal vaginitis more likely.