What is a clue cell in bacterial vaginosis diagnostics?

Clue Cells

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.

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.

     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. 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 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). 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.