Lubricant, mucus, and other contaminant materials as a potential source of interpretation errors in ThinPrep cervical cytology.

Objective: To investigate the possibility of the occurrence of errors in the interpretation of cervical smears in the presence of lubricant, mucus and other contaminant particles in ThinPrep (TP) technique (Cytyc Corp., Boxborough, MA) liquid-based cervical cytology. Materials and Methods: Four thousands sixty-eight TP cervical smears were reviewed over a 12-month period. Those cases that initially had caused interpretation errors in which lubricant, mucus, and other contaminant materials were confused with infectious agents or epithelial abnormalities among the primary screening cytotechnologists and pathologists were selected for our study. These cases were retrieved from the cytology unit's registered logbook. The possibility of these detected lubricant, mucus, and other contaminant materials in these cases to cause misinterpretation for randomly selected pathologists and cytotechnologists who were blinded for the study was further investigated. Three cytotechnologists and 2 pathologists were independently asked to give their opinions on each case without their prior knowledge of the selected cases. Results: Only 15 cases out of 4068 were found to cause interpretation errors. Five different contaminant patterns were detected. The main potential misinterpretations included secondary diagnosis that is confused mainly with infectious agents. However, other contaminants were even misinterpreted as high-grade squamous epithelial abnormalities. Conclusions: This study illustrates the potential of lubricant, mucus, and foreign body contaminant materials to cause interpretation errors in TP cervical cytology. Although liquid-based preparation reduces the obscuring effect of these materials, the unusual appearance of some of these particles in TP cervical smears not only can mimic infectious microorganisms, but also squamous dyskaryosis. This can lead to serious interpretation errors for the inexperienced cytotechnologists and pathologists, which subsequently can have an effect on the women's management.