From the Guidelines
Brown vaginal discharge requires a thorough medical evaluation to determine its cause, starting with a comprehensive history and physical examination, including a pelvic exam, as recommended by the American Academy of Pediatrics 1. The workup should include testing for sexually transmitted infections (STIs) like gonorrhea and chlamydia, bacterial vaginosis, and trichomoniasis through vaginal swabs.
- A wet mount microscopy can identify clue cells, yeast, or trichomonads, with a sensitivity of 50-70% for trichomoniasis 1.
- Consider a Pap smear if due or if there are concerns about cervical abnormalities. Brown discharge often represents old blood mixed with normal vaginal secretions and may occur with menstrual cycle variations, hormonal contraceptive use, or during early pregnancy.
- If infection is suspected, treatment depends on the specific pathogen identified—metronidazole 500mg twice daily for 7 days for bacterial vaginosis or trichomoniasis, as outlined in the Centers for Disease Control and Prevention guidelines 2.
- For persistent or recurrent brown discharge, further evaluation with transvaginal ultrasound or endometrial biopsy may be necessary to rule out endometrial polyps, fibroids, or malignancy, especially in women over 40 or those with risk factors. Patients should be advised to avoid douching and use condoms to prevent STIs if applicable, as douching has been associated with an increased risk of bacterial vaginosis and other infections 2.
From the Research
Brown Vaginal Discharge Workup
- The workup for brown vaginal discharge involves diagnosing the underlying cause, which can be infectious or non-infectious in nature 3, 4.
- Common infectious causes of vaginitis include bacterial vaginosis, vulvovaginal candidiasis, and trichomoniasis, which can be diagnosed using laboratory tests such as wet mount preparations, pH determination, and cultures 3, 4.
- Bacterial vaginosis is characterized by a milky discharge, pH greater than 4.5, positive whiff test, and clue cells in a wet-mount preparation, and is typically treated with oral metronidazole 3.
- Vulvovaginal candidiasis can be diagnosed using microscopic examination of a sample from the lateral vaginal wall and is typically treated with topical azole or oral fluconazole 3.
- Trichomoniasis can be diagnosed using culture and DNA probe testing and is typically treated with a single 2-g oral dose of metronidazole 3, 4.
Diagnostic Tests
- Wet mount preparations are a useful diagnostic tool for vaginitis, but may have a high false-negative rate for trichomoniasis 3, 4.
- Vaginal pH determination can help diagnose bacterial vaginosis and trichomoniasis 3, 4.
- Cultures can be helpful in diagnosing vulvovaginal candidiasis and trichomoniasis, especially in cases of recurrent or complicated infections 3, 4.
- Pap smears can be used to diagnose bacterial vaginosis, but are not a reliable diagnostic tool for this condition 5.
- The presence of atypical squamous cells of undetermined significance (ASCUS) on a Pap smear does not appear to be affected by treatment with metronidazole 6.
Treatment Options
- Metronidazole is the standard treatment for bacterial vaginosis and trichomoniasis 3, 4.
- Topical azole and oral fluconazole are effective treatments for vulvovaginal candidiasis 3.
- Treatment of ASCUS Pap smears with topical metronidazole does not appear to increase the rate of resolution in subsequent Pap smears 6.