Clue cells in diagnosis of bacterial vaginosis

The detection of clue cells is a component of the Amsel criteria which is used in the diagnosis of bacterial vaginosis

• clue cells (epithelial cells covered with small Gram-negative/Gram-variable rods) are detected by Gram staining of vaginal discharge by standard procedures and examination under oil immersion. Presence of clue cells in at least 20% of the oil immersion fields is considered positive by the Amsel criteria (1)
• the presence of 'clue cells' has been found to be the most sensitive component of the Amstel criteria (2)
  
  

Bacterial vaginosis is conventionally diagnosed using Amsel criteria

• the presence of any three of the following four criteria is considered to be consistent with the presence of bacterial vaginosis:
  • characteristic thin, homogenous vaginal discharge,
  • vaginal pH greater than 4.5,
  • release of a fishy amine odor on addition of 10% KOH (whiff test),
  • and demonstration of clue cells in more than 20% of the total cell population

Reference:

• 1) Amsel R et al. Non-specific vaginitis: diagnostic techniques and microbial and epidemiologic associations. Am J Med 1983; 74: 14-22.
• 2) Modak T et al. Diagnosis of bacterial vaginosis in cases of abnormal vaginal discharge: comparison of clinical and microbiological criteria. J Infect Dev Ctries. 2011 May 28;5(5):353-60.