Liquid-based preparation in cervical cytology screening

Abstract

The conventional smear has been very useful in detecting pre-cancerous lesions of the cervix. In recent years the UK screening programme has resulted in a 7% reduction annually in invasive cervical carcinoma. However the conventional smear has many limitations including a significant false negative and false positive rate and a significant unsatisfactory rate. Specimen quality is a problem with conventional Pap smears, with the presence of blood, inflammation and mucus often obscuring potential diagnostic cells leading to an unacceptably high unsatisfactory and suboptimal rate. In an attempt to address these limitations associated with the conventional smear various new techniques of smear preparation and screening have been developed.Liquid-based cytology (LBC) is proving to be a very useful alternative to the conventional method of smear preparation. The method is based on the suspension of cells in preservative fluid rather than smearing on a glass slide. The final result is an even distribution of ‘wet’ well-fixed cells with a greater harvesting of cells and a reduction in debris, polymorphs and mucus in a defined area on a slide. This leads to a reduction in unsatisfactory smears and an improved detection rate of both low grade and high grade dyskaryosis. An additional advantage of LBC is the adjunctive testing facility for human papillomavirus (HPV) and chlamydia and also automated screening.