What is the cause of a fishy smelling vaginal discharge?

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Last updated: May 26, 2025View editorial policy

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Differential Diagnosis for Fish Smell Vaginal Discharge

  • Single Most Likely Diagnosis
    • Bacterial Vaginosis (BV): This is the most common cause of fishy-smelling vaginal discharge. BV occurs when there is an imbalance in the normal vaginal flora, with an overgrowth of anaerobic bacteria. The fishy odor is due to the production of amines by these bacteria.
  • Other Likely Diagnoses
    • Trichomoniasis: A sexually transmitted infection caused by the parasite Trichomonas vaginalis. It can cause a foul-smelling vaginal discharge, which may be greenish-yellow in color.
    • Vulvovaginal Candidiasis: Although typically associated with a yeasty odor, some cases of candidiasis can produce a fishy smell, especially if there is a secondary bacterial infection.
  • Do Not Miss Diagnoses
    • Cervical Cancer: Although rare, cervical cancer can cause abnormal vaginal discharge with a foul odor. It is crucial to rule out this diagnosis, especially in women with risk factors or abnormal Pap smear results.
    • Pelvic Inflammatory Disease (PID): PID is a serious infection of the female reproductive organs that can cause abnormal vaginal discharge, pelvic pain, and other symptoms. If left untreated, PID can lead to severe complications, including infertility and ectopic pregnancy.
  • Rare Diagnoses
    • Desquamative Inflammatory Vaginitis (DIV): A rare condition characterized by a purulent vaginal discharge with a strong odor, often accompanied by vaginal bleeding and pain.
    • Foreign Body in the Vagina: A retained foreign body, such as a tampon or condom, can cause a foul-smelling vaginal discharge due to the accumulation of bacteria and debris.
    • Genitourinary Fistula: An abnormal connection between the vagina and the urinary tract or rectum can cause recurrent vaginal infections and foul-smelling discharge.

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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