Accuracy of reading liquid based cytology slides using the ThinPrep Imager compared with conventional cytology: prospective study.
OBJECTIVE
To compare the accuracy of liquid based cytology using the computerised ThinPrep Imager with that of manually read conventional cytology.


METHODS
Prospective study.


METHODS
Pathology laboratory in Sydney, Australia.


METHODS
55,164 split sample pairs (liquid based sample collected after conventional sample from one collection) from consecutive samples of women choosing both types of cytology and whose specimens were examined between August 2004 and June 2005.


METHODS
Primary outcome was accuracy of slides for detecting squamous lesions. Secondary outcomes were rate of unsatisfactory slides, distribution of squamous cytological classifications, and accuracy of detecting glandular lesions.


RESULTS
Fewer unsatisfactory slides were found for imager read cytology than for conventional cytology (1.8% v 3.1%; P<0.001). More slides were classified as abnormal by imager read cytology (7.4% v 6.0% overall and 2.8% v 2.2% for cervical intraepithelial neoplasia of grade 1 or higher). Among 550 patients in whom imager read cytology was cervical intraepithelial neoplasia grade 1 or higher and conventional cytology was less severe than grade 1, 133 of 380 biopsy samples taken were high grade histology. Among 294 patients in whom imager read cytology was less severe than cervical intraepithelial neoplasia grade 1 and conventional cytology was grade 1 or higher, 62 of 210 biopsy samples taken were high grade histology. Imager read cytology therefore detected 71 more cases of high grade histology than did conventional cytology, resulting from 170 more biopsies. Similar results were found when one pathologist reread the slides, masked to cytology results.


CONCLUSIONS
The ThinPrep Imager detects 1.29 more cases of histological high grade squamous disease per 1000 women screened than conventional cytology, with cervical intraepithelial neoplasia grade 1 as the threshold for referral to colposcopy. More imager read slides than conventional slides were satisfactory for examination and more contained low grade cytological abnormalities.
Davey
Elizabeth
E
Screening and Test Evaluation Program, School of Public Health, University of Sydney, NSW 2006, Australia. daveye@health.usyd.edu.au
d'Assuncao
Jefferson
J
Irwig
Les
L
Macaskill
Petra
P
Chan
Siew F
SF
Richards
Adele
A
Farnsworth
Annabelle
A
D001706:Biopsy; D002294:Carcinoma, Squamous Cell / Q000473:pathology*; D003584:Cytological Techniques / Q000592:standards; D005069:Evaluation Studies as Topic; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D002583:Uterine Cervical Neoplasms / Q000473:pathology*; D014626:Vaginal Smears; D002578:Uterine Cervical Dysplasia / Q000473:pathology*