Differential Diagnosis for Chronic Brown Vaginal Discharge with Odor

• Single Most Likely Diagnosis
  • Bacterial Vaginosis (BV): This is the most common cause of vaginal discharge in women of reproductive age. The symptoms of BV include a thin, white or gray, homogeneous discharge with a fishy odor, which can sometimes appear brown due to the presence of blood or when the discharge is old. The justification for this being the single most likely diagnosis is based on its high prevalence and the match between the symptoms described and those typical of BV.
• Other Likely Diagnoses
  • Trichomoniasis: Caused by the protozoan Trichomonas vaginalis, this infection can lead to a greenish-yellow, frothy discharge with an unpleasant odor. While the discharge color doesn't exactly match the description, the variability in presentation and the presence of odor make it a plausible diagnosis.
  • Vulvovaginal Candidiasis: Although typically characterized by a thick, white, cottage cheese-like discharge, some cases can present with a thinner, more watery discharge that might appear brown, especially if there's bleeding. The odor is usually less pronounced than in BV but can still be present.
• Do Not Miss Diagnoses
  • Cervical Cancer: Although rare, cervical cancer can cause abnormal vaginal bleeding, which might appear as a brown discharge, especially if the bleeding is intermittent and old. The presence of a foul odor could be indicative of tumor necrosis. Given the potentially devastating consequences of missing this diagnosis, it's crucial to consider it, especially in women who are not up to date with their cervical cancer screening.
  • Pelvic Inflammatory Disease (PID): PID can cause a variety of symptoms, including abnormal vaginal discharge, which might be brown if there's associated bleeding. The odor can be foul due to the infection. PID is a serious condition that requires prompt treatment to prevent long-term complications like infertility and chronic pelvic pain.
• Rare Diagnoses
  • Foreign Body: The presence of a foreign body in the vagina, such as a retained tampon, can cause a foul-smelling discharge. The discharge might appear brown if the object has been in place for a while, causing tissue necrosis and bleeding.
  • Desquamative Inflammatory Vaginitis (DIV): A rare condition characterized by a purulent, greenish or brownish discharge with a bad odor. It's often associated with significant vaginal inflammation and can be challenging to diagnose due to its rarity and nonspecific symptoms.