‘WHERE DO MY BITS OF CERVIX GO?’ DR IRENE REGAN ON WHAT WOMEN SHOULD KNOW ABOUT SMEARS
“Where are the slides with bits of my cervix on them?” demanded Fine Gael TD Kate O’Connell of HSE officials at an Oireachtas committee hearing.
We put this and other questions to Dr Irene Regan, president of the Academy of Clinical Science and Laboratory Medicine, who sets out the facts involved in the process of reading smear tests.
Dr Regan says she can attest to best practice in Irish laboratories only.
The best time for a smear test is 10 to 14 days after the first day of a woman’s menstrual cycle. Cells are brushed from inside the cervix, preserved in liquid in standardised bottles and dispatched from GP surgeries to one of three laboratories, two in Ireland, the other in the US.
According to Dr Regan, 45pc of smears go to a US laboratory, Quest Diagnostics; 45pc go to MedLab Pathology, part of the Sonic Healthcare group in Dublin; and 10pc to the laboratory at the Coombe Hospital in Dublin.
Smears taken at Well Woman clinics or from the Carlow and Kilkenny area are read in the Coombe. Smears from the rest of Leinster are sent to the US while smears from the rest of Ireland go to MedLab.
Cells from the smear samples are transferred onto glass slides. Each slide is subject to a primary and secondary examination under the microscope by expert medical scientists. For the primary examination, medical scientists are required to examine each slide for an absolute minimum of six minutes, viewing the entire slide, according to best practice. The secondary examination takes less time and is performed by a second medical scientist, blinded to the findings of the primary screen.
If the expert medical scientists reach different conclusions on the reading, the slide is referred to a more senior medical scientist for review. The ‘checker’ forwards the slide to a consultant cytopathologist if there is any suspicion of abnormality.
Abnormalities are graded from low grade (CIN 1) to high grade (CIN 2 or CIN 3).
A ‘false positive’ reading occurs when a slide is interpreted as abnormal but abnormalities are not present. A ‘false negative’ occurs where abnormalities are present in the stained slide but are missed or misinterpreted.
Medical scientists are required to reach individual ‘pick-up’ or detection rates of 95pc or greater for high-grade abnormalities, and greater than 90pc for all abnormalities.
Slides, and digital images, must be retained by laboratories for 30 years.
The overall capacity of the population screen to detect abnormalities in a woman is about 65pc. The examination of prepared slides should detect abnormalities greater than 90pc of the time.