Inflammatory / infectious

Bacterial vaginosis

Topic Completed: 2 October 2006

Minor changes: 5 March 2020

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PubMed search: Bacterial Vaginosis Inflammation

Farnaz Hasteh, M.D.
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Cite this page: Hasteh F. Bacterial vaginosis. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/cervixcytologybacterialvaginosis.html. Accessed December 3rd, 2021.
Definition / general
  • Common cause of vaginal discharge in young women, usually due to multiple microbes
  • Also called "shift in flora", Gardnerella vaginalis, "clue cells"
  • Most common cause of abnormal discharge in young women
  • Common finding in women with SIL (HPV infection)
  • Uncommon in postmenopausal women, except those with hormonal replacement therapy
  • Risk factors include multiple sexual partners, IUD, prior pregnancy, medication, spermicides and smoking
  • Gardnerella vaginalis in the most common cause (eMedicine)
  • Usually it is multimicrobial (Gardnerella vaginalis, Prevotella, Mobiluncus, peptostreptococci, Mycoplasma hominis and Ureaplasma urealyticum)
  • Increases in vaginal pH (> 4.5) can cause Gardnerella vaginalis to adhere more to squamous cells, causing the morphologic appearance of "clue cells"
Clinical features
  • Discharge with "fishy" or ammonia-like odor in some patients
  • Most patients are asymptomatic
  • Pap smear is 80% sensitive and 87% specific; presence of "clue cells" is more sensitive and specific (Acta Cytol 2005;49:634)
Prognostic factors
  • Complications are rare and include PID, infertility, postoperative infection, premature labor or low birth weight babies
Cytology description
  • Clue cells are squamous cells covered by coccobacilli with extension to the cell edges (velvety coat or shaggy appearance)
  • The entire cell does not need to be covered
  • Lactobacilli and inflammatory cells are absent, unless there is another infectious process
  • The small coccobacilli form a granular blue background (sandy background) on conventional smears
  • In liquid based cytology, the background is cleaner than with conventional smears
Cytology images

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Conventional smears

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