What is a clue cell in bacterial vaginosis diagnostics?

Clue Cells

TL;DR

Clue cells are epithelial cells found in the vagina that, when coated in bacteria, indicate bacterial vaginosis (BV). These cells, distinguished by their bacterial biofilm, are essential in diagnosing BV, highlighting the importance of Amsel’s criteria in identifying this common vaginal condition.

A clue cell is a type of cell found in the vagina, an epithelial cell, that when examined under a microscope is found to have a cluster of bacteria attached to it.​1,2​

Clue cells are distinctive in appearance, as they are covered in bacteria and what’s known as a bacterial biofilm. These biofilms are produced by a number of bacteria and yeasts, including healthy bacteria, but clue cells are specific to bacterial vaginosis.

The name ‘clue cell’ was invented by a pair of researchers, Gardner and Dukes, who were the first researchers looking into bacterial vaginosis and Gardnerella vaginalis.

G. vaginalis was once believed to be the main cause of BV, but this doesn’t appear to be true – there are many contributors and protagonists in the BV story.​3​

What is an epithelial cell?

Epithelial cells are a type of skin cell, which you can think of as the outer layer of our skin cells. These cells slough off and are lost as part of our natural skin function.​4​

In the vagina, this loss is via normal vaginal secretions – what you know of as discharge. Gravity takes care of these shed cells as they slough off, and come out into your underwear.

This sloughing is a slow process, but the more vaginal fluids you have, the more skin cells make their exit.

What does a clue cell look like?

When these cells are coated in bacteria in a very specific way, it indicates a vaginal problem, namely bacterial vaginosis (BV). ​5​

Looking for clue cells is part of a group of tests usually performed, with the collection of tests for BV known as Amsel’s criteria. Amsel’s criteria is a pH test, the whiff test, and a microscopic examination in your doctor’s office to see if you have clue cells.

References

  1. 1.
    Money D. The Laboratory Diagnosis of Bacterial Vaginosis. Canadian Journal of Infectious Diseases and Medical Microbiology. Published online 2005:77-79. doi:10.1155/2005/230319
  2. 2.
    Swidsinski A, Loening-Baucke V, Swidsinski S, Sobel JD, Dörffel Y, Guschin A. Clue Cells and Pseudo Clue Cells in Different Morphotypes of Bacterial Vaginosis. Front Cell Infect Microbiol. Published online May 27, 2022. doi:10.3389/fcimb.2022.905739
  3. 3.
    Patterson JL, Stull-Lane A, Girerd PH, Jefferson KK. Analysis of adherence, biofilm formation and cytotoxicity suggests a greater virulence potential of Gardnerella vaginalis relative to other bacterial-vaginosis-associated anaerobes. Microbiology. Published online February 1, 2010:392-399. doi:10.1099/mic.0.034280-0
  4. 4.
    O’Hanlon DE, Gajer P, Brotman RM, Ravel J. Asymptomatic Bacterial Vaginosis Is Associated With Depletion of Mature Superficial Cells Shed From the Vaginal Epithelium. Front Cell Infect Microbiol. Published online March 10, 2020. doi:10.3389/fcimb.2020.00106
  5. 5.
    Anton L, Ferguson B, Friedman ES, Gerson KD, Brown AG, Elovitz MA. Gardnerella vaginalis alters cervicovaginal epithelial cell function through microbe-specific immune responses. Microbiome. Published online August 4, 2022. doi:10.1186/s40168-022-01317-9


Jessica Lloyd - Vulvovaginal Specialist Naturopathic Practitioner, BHSc(N)

Jessica is a degree-qualified naturopath (BHSc) specialising in vulvovaginal health and disease, based in Melbourne, Australia.

Jessica is the owner and lead naturopath of My Vagina, and is a member of the:

  • International Society for the Study of Vulvovaginal Disease (ISSVD)
  • International Society for the Study of Women's Sexual Health (ISSWSH)
  • National Vulvodynia Association (NVA) Australia
  • New Zealand Vulvovaginal Society (ANZVS)
  • Australian Traditional Medicine Society (ATMS)
SHARE YOUR CART