Snapshot A 45-year-old woman presents to an urgent care clinic for green foul-smelling vaginal discharge for the past few days. She reports that she has had unprotected sex with one new sexual partner, but she wasn’t worried about sexually transmitted diseases. She has not had any fevers or chills but has had dysuria and dyspareunia. She also noticed postcoital bleeding yesterday. Pelvic exam shows green foul-smelling vaginal discharge and an erythematous vulva. The vaginal pH is 5.5 and a wet mount shows motile trichomonads. She is started on metronidazole. Introduction Sexually transmitted diseases caused by protozoa include Trichomonas vaginalis Classification T. vaginalis protozoa causes vulvovaginitis in women causes urethritis in men a sexually transmitted disease Epidemiology demographics women > men risk factors new sexual partners multiple sexual partners injection drug use unprotected sex Pathogenesis protozoa thrives in the vagina or urethra it attaches to the walls of the vagina, causing inflammation Associated conditions HIV infection herpes simplex virus type 2 Prognosis asymptomatic in men may recur Presentation Symptoms dyspareunia dysuria vulvar itching and burning postcoital bleeding Physical exam malodorous green discharge "strawberry" cervix vulvovaginal erythema Studies Labs vaginal pH 5-6 wet mount microscopy motile trichomonads positive culture from urethral swab, urine, or semen in men also used to confirm diagnosis in women if wet mount is equivocal Making the diagnosis most cases are clinically diagnosed and confirmed on wet mount microscopy Differential Vulvovaginal candidiasis distinguishing factors thick white curd-like vaginal discharge often very itchy with vulvar erythema and edema Bacterial vaginosis distinguishing factors thin white-gray discharge fishy odor clue cells on wet mount microscopy normal vulva Treatment Management approach sexual partners should be treated as this is a sexually transmitted disease Conservative abstinence indication for all patients until treatment is complete Medical metronidazole indication all patients tinidazole indication patients with contraindication to metronidazole Complications Premature rupture of membranes Prematurity of fetus