DScreening for Ca Cervix:-Cytology based screening programmes are labour intensive and logistically burdensome

Cytology based screening programmes are labour intensive and logistically burdensome. They require multiple visits by the women for various reasons like screening obtaining the results follow up investigations and treatment in cases of abnormal smears . Many programmatic aspects need to be taken into consideration for the programme to achieve the maximum potential public health benefit such as compliance of the women to the screening procedures obtaining an adequate smear transport of samples to the nearest secondary or tertiary care facility for further processing and analysis. Thus despite the low consumables cost high quality cytology is expensive in absolute terms and may not necessarily be the most cost effective option for screening several new technologies like the liquid based cytology and the automated pap smears are being explored.

In liquid cytology the cells are collected using a very small brush that is broken off into a small pot containing preservative solution. In  the cytology laboratory the sample is filtered or centrifuged to remove excess blood and debris and the cells are then transferred to the slide in a mono layer thus obtaining uniformity of the cell  population in each sample. It has logistical and operational advantages such as interpretation at higher speed lower rate of unsatisfactory smears and possibility of ancillary molecular testing using remnant fluid. LBC is more expensive than conventional cytology and requires additional supplies and sophisticated equipment. In a meta analysis comparing conventional pap with LBC no difference was found in the relative sensitivity. Similarly no difference was found in the relative specificity when high grade squamous intraepithelial lesions and low grade squamous intraepithelial lesions were considered as cutoff .  But a lower pooled specificity was found for LBC when presence of atypical squamous cells of underdetermined significance and above were included .

In Automated pap smears testing the material on the slide is reviewed and scored based on an algoilthm . This includes variety of visual characteristics such as shape and optical density of the cells as to the likelihood of an abnormality being present . Auto pap selects a sample of slides for manual re screening that are enriched with abnormalities thereby including most of the slides that exceed a certain threshold for the likelihood of abnormal cells in contrast to random rescreening In autocyte screen a human reviewer after looking at the various cell images that are presented determines whether a manual review is required. The reviewer needs to enter an opinion . if the findings of both the reviewer and the computer are reported as normal then no further review is needed and the diagnosis is reported as within normal limits . Manual review is undertaken for cases which are designated by either the cytologist or the computer ranking as abnormal.

Visual Inspection Methods

It has been difficult to establish and maintain effective cervical cytology programs in developing countries due to lack of resources trained man power infrastructure and the requirement of multiple visits. Hence alternative low cost and effective screening methods based on visual examination of the cervix that require simple equipment and relatively brief training have  been explored for the control of cervical cancer in low resource settings.