Vaginal discharge is a common complaint in sexually active women. Normal discharge in premenopausal women is non-irritant, non-offensive, not blood-stained and has a pH of 3.5-4.5. Normal vaginal flora includes Corinebacterium, Bacteroides, Peptostreptococcus, Mobiluincus, Gardnerella, Mycoplasma and Candida spp. The acidic pH, which serves a protective function, is maintained by lactobacilli, which produce lactic acid. There are no glands in the vagina. Vaginal discharge originates predominantly from vaginal desquamation, bacteria and secretions from the cervix and upper genital tract. It may be, therefore, a presentation of upper genital tract disease including infection and, rarely, malignancy.
The important symptoms in women with abnormal vaginal discharge are pruritis, odor, intermenstrual bleeding (including postcoital bleeding) and abdominal pain. On examination, in addition to the color and nature of the discharge itself, the presence of vulvitis, vaginitis and cervicitis should be noted.
Whilst the commonest causes of vaginal discharge, bacterial vaginosis and candidiasis, are not sexually transmitted, the same symptoms can be caused by other conditions and the possibility of an sexually transmitted infection should be considered. Foreign bodies like retained tampons usually result in vaginal discharge. Atrophic vaginitis and allergic reactions to bubble baths, douches and other cleansing or perfumed agents can cause soreness and itching.
If an sexually transmitted infection is suspected, appropriate tests should be performed or the patient referred to a genitourinary medicine clinic. It is common practice to treat empirically if an sexually transmitted infection is not suspected and many patients self-medicate with, e.g., antifungal therapy. However, it is important that women should be examined and investigated if symptoms persist.
The flagellated protozoan Trichomonas vaginalis (commonly known as TV) causes trichomoniasis, which is almost always sexually transmitted. It is uncommon, compared with bacterial vaginosis and candidiasis, and is asymptomatic in up to half of cases. The incubation period of T. vaginalis is 1 to 3 weeks. It affects the vagina and urethra and has no long-term complications. It is a cause of nonspecific urethritis (NSU) in men. The diagnosis of trichomoniasis should alert the clinician to test for presence of other sexually transmitted infections.
Clinical features range from no symptoms or signs to a severe vulvo-vaginitis with profuse vaginal discharge and abdominal discomfort, There is usually marked erythema of the vaginal epithelium and the classic ‘strawberry cervix’ is occasionally seen. The discharge may be malodorous, blood-stained and frothy and yellow/green in color.
The diagnosis, suspected by clinical features and a vaginal pH above 4.5, is made by culture or microscopy analysis of a wet mount from a high vaginal swab. As it has a low specificity, trichomoniasis suspected on cervical cytology should be confirmed by culture or microscopy analysis. Both trichomoniasis and bacterial vaginosis cause a raised vaginal pH, but the former can usually be distinguished from the latter by the presence of vaginal inflammation.
Oral metronidazole is recommended as either 2 g in a single dose or 400 mg twice a day for 5 days. The single high-dose regimen should be avoided in pregnancy. Male partners should be examined and tested for trichomoniasis and other sexually transmitted infections. As culture or microscopy analysis for trichomoniasis is insensitive in men, partners should be treated for it, even if the organism is not detected.
A test of cure should be performed in women. Successful treatment is dependent upon patient compliance and the simultaneous treatment of her partner (s). If resistance occurs and re-infection has been excluded, advice on further treatment should be obtained from a microbiologist or genitourinary medicine physician.