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Liquid based cytology for risk-adapted cervical screening

In the early 70?s, there were two projects in Germany for developing computer-assisted cervical screening. It was soon realised, however, that »machine-readable« cytological preparations had to fulfil certain criteria which are difficult to achieve by conventional Pap smears, i.e. isolated cells in one optical plain (monolayer), high contrast between nuclei, cytoplasm and background and clear background. The first issue could be solved by single cell preparation (monodispersion), the last one by cell separation and cleaning. This was the advent of liquid based cytology (LBC). Currently, there are three LBC-systems used in Germany: ThinPrep®, SurePath and the PapSpin®-method. There are some differences but even more similarities between cytomorphology of LBC and conventional Pap smears. The main difference is the clear background provided by LBC, which makes it easier to recognise and interpret abnormal cells. Until now, some evidence has accumulated that liquid-based cytological methods offer the following advantages over traditional smear techniques: a) a reduction in the proportion of inadequate specimens, b) an improvement in sensitivity and c) a possible reduction in specimen interpretation times. This conclusion, however, could not be supported by all comparative studies and meta-analyses. Nevertheless, it is an unequivocal advantage of the LBC method that it provides a platform for multimodal risk-adapted cervical screening. This could lead to a positive predictive value (PPV) of 88.2% for the detection of > CIN II using the combination of LBC with type-specific HPV/PCR test and DNA-cytometry in our hands. In the USA, 98% of Pap tests are liquid based. This reflects the enormous popularity of the method amongst cytologists This has been demonstratively expressed by the director of cytopathology of the University of Vermont who said, that he was »fed up screening poorly preserved, air-dried, blood stained, conventional slides of varying depth of focus«, which, among others, can fully be eliminated by LBC.

CME Prakt Fortbild Gynakol Geburtsmed Gynakol Endokrinol 2014; 10(3): 274–290

ThinPrep, SurePath, PapSpin, multimodal screening

Reinhard Bollmann
Institut für Pathologie Bonn-Duisdorf, Bonn
Reviewer: Wolfgang Kühn, Berlin,
und Jan Dolezil, Hamburg

Bollmann R. Flüssigkeitszytologie ... Gynakol Geburtsmed Gynakol Endokrinol 2014; 10(3): 274–290 publiziert 30.11.2014 ©akademos Wissenschaftsverlag 2014 ISSN 1614-8533