Excessive mucus, as well as blood and inflammation, can be problematic in the processing and screening of liquid-based cervical Pap preparations by interfering in the process of cell retrieval onto specimen filters or slides. This study compares the capacity of the BD SurePath and ThinPrep liquid-based Papanicolaou (Pap) tests to handle mucus-laden specimens.
A 100 μL volume of pooled cervical epithelial cells was added to BD SurePath and ThinPrep liquid Pap test vials. Aliquots of cervical mucus that had been collected and pooled from previously processed mucus-rich Pap specimens were added to each series of test vials in amounts of 250 μL, 500 μL, 1000 μL, and 2000 μL. The vials were then routinely processed on their respective instruments and the test slides evaluated for cellularity of the squamous cell component.
The BD SurePath test specimens showed no reduction of the squamous cell component resulting from the addition of any of the aliquots of mucus. The ThinPrep test specimens showed a marked loss of cellularity upon the addition of the first aliquot of mucus, with large areas of the filters showing nearly complete absence of squamous cells.
Excessive mucus remains a potentially limiting factor in the ThinPrep Pap system. This appears to be the result of direct obstruction of the filtration membrane causing a markedly diminished retrieval of squamous epithelial cells and potentially impacting disease detection. The BD SurePath system, conversely, manages mucus by a cell enrichment process, which results in undiminished cell recovery as observed in this study's test conditions.