Dr. Tony Holohan:

I am not a pathologist either but perhaps, as a medical doctor, I am a little closer to the field. To explain, the process of smear taking involves a pathologist, or a technician in the first instance, who examines a sample through a microscope and makes a subjective judgment of subtle changes and abnormalities. The reality is that it is not a perfect science. That is part of the reason the organisation of any proper organised screening programme, such as the one we introduced in this country in 2008, builds in mechanisms to try to take account of the known limitations of the test. It builds in mechanisms to monitor the quality of the operation of that programme when it is in operation.