Manual Cytology Preferred to Automatic Method

Manual reading of cervical smear slides is superior to automation-assisted reading at detecting abnormal cells.

Technology is available which can assist in cervical screening by automatically detecting abnormal fields on a slide and presenting them on an automated microscope, and is analogous to manual cytological microscopy.

Scientists at the University of Manchester (Manchester, UK), compared automation-assisted reading of cervical cytology with manual reading using the histological end point of cervical intraepithelial neoplasia grade II (CIN2) or worse (CIN2+). Samples were obtained from women aged 25-64 years undergoing primary cervical screening in Greater Manchester (UK), with small proportions from women outside this age range and from women undergoing colposcopy. Over 70,000 samples were randomized and assessed either by automated and manual reading or by manual reading only. The study was carried out between March 1, 2006, and February 28, 2009.

Liquid-based cytology samples were obtained in primary care, and a small number of abnormal samples were obtained from local colposcopy clinics, from different women, in order to enrich the proportion of abnormals. All of the samples were read in a single large service laboratory. Liquid residues used for Human papillomavirus (HPV) triage were tested in specialist virology laboratory. Histopathology was read by a specialist gynecological pathology team blinded to HPV results and type of reading.

The principal finding was that automated reading was 8% less sensitive relative to manual, 6.3% in absolute terms. The FocalPoint Slide Profiler (Becton Dickinson, Franklin Lakes, NJ, USA), especially "No Further Review” was very reliable and, if restricted to routine screening samples, as less than 1% of CIN2+ would have been missed. Automated and manual were very similar in terms of cost-effectiveness despite a 60% - 80% increase in productivity for automation-assisted reading. The authors concluded that the inferior sensitivity of automation-assisted reading for the detection of CIN2+, combined with an inconsequential increase in specificity, suggests that automation-assisted reading cannot be recommended for primary cervical screening.

Henry Charles Kitchener, MD, professor of gynecological oncology and lead author said, "Although automated reading could achieve productivity gains in terms of the numbers of slide checked, on the basis of this evidence there does not appear to be sufficient grounds to recommend automation.” The trial also found that the cytoscreeners preferred manual reading as automation-assisted reading was monotonous. The article was published in January 2011, in Lancet Oncology .

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University of Manchester
Becton Dickinson