A clue cell is a vaginal epithelial cell observed during microscopic analysis. It indicates a distinct change in appearance due to bacterial adherence, providing important information for diagnosing certain vaginal conditions. This specialized cellular finding guides healthcare professionals in their assessment.
Defining a Clue Cell
A clue cell is a vaginal epithelial cell that appears fuzzy or stippled under a microscope, lacking the sharp, distinct edges of a normal cell. This characteristic appearance results from a dense coating of bacteria on its surface. The bacteria are so numerous that they obscure the cell’s borders and give it a granular or “moth-eaten” look.
The term “clue” refers to its diagnostic significance, providing a clear indication of a particular condition. These cells were first described in 1955 by Gardner and Dukes as a sign of bacterial vaginosis. Gardnerella vaginalis and other anaerobic bacteria are most commonly associated with this phenomenon.
What Clue Cells Signify
The presence of clue cells is a strong indicator of bacterial vaginosis (BV). BV is a common vaginal condition characterized by an imbalance in the natural vaginal flora, where certain bacteria like Gardnerella vaginalis overgrow, leading to a decrease in protective Lactobacillus species.
While BV can be asymptomatic, it often presents with symptoms like an abnormal vaginal discharge that may have a “fishy” odor. The identification of clue cells is a significant component of the diagnostic criteria for BV. The condition is not considered a sexually transmitted infection, but sexual activity can be a risk factor due to changes in vaginal chemistry.
Identifying Clue Cells
Clue cells are identified through microscopic examination of a vaginal wet mount. This involves collecting a sample of vaginal discharge, mixing it with a saline solution, and observing it under a light microscope. Healthcare professionals look for vaginal epithelial cells with fuzzy or indistinct borders caused by adherent bacteria.
Their presence is one of several factors evaluated for a BV diagnosis, often as part of Amsel’s criteria. Other microscopic findings in BV include a reduced number of Lactobacillus bacteria and the absence of white blood cells, which are present in other types of vaginal infections. For a BV diagnosis, more than 20% of the epithelial cells on the wet mount should be clue cells.