Rapid Pre-Screening Is More Sensitive in Liquid-Based Cytology than in Conventional Smears

Abstract

Rapid pre-screening (RPS) is a useful tool to measure and improve performance in the cytology laboratory. Whether RPS is more or less effective in liquid-based cytology than in conventional smears is unknown. We compared the estimated sensitivity in a laboratory of 11 cytotechnologists which converted from conventional smears to SurePath™ (Becton Dickinson, Franklin Lakes, N.J., USA) liquid based cytology. In the 9 months prior to conversion, 23,286 smears were screened compared with 30,610 smears in the 12 months immediately after conversion. The estimated sensitivity of rapid pre-screening for 90 s improved significantly with liquid based cytology for all abnormalities (58.7 vs. 68.7%, p < 0.001), atypical squamous cells of undetermined significance + low-grade squamous intra-epithelial lesion (52.6 vs. 63.1%, p < 0.001), and high-grade squamous intra-epithelial alone (76.2 vs. 85%, p < 0.001). Histologic follow up for 156 cases identified by rapid pre-screening of SurePath slides showed 32 (21%) cases of CIN1 or greater and 18 cases (12%) with CIN3 or worse. We conclude that rapid pre-screening is significantly more sensitive in liquid-based cytology compared with conventional smears, and detects significant lesions that are missed by routine screening.

Improvement in the routine screening of cervical smears

“…The sensitivity of rapid prescreening was approximately 60% higher than that of 100% rapid review in detecting abnormalities as severe as ASC-US or worse, and although no other studies have yet been carried out to compare these methods, these findings are in agreement with other studies that have evaluated rapid prescreening and 100% rapid review separately. 3,4,9,19,20,[28][29][30][31][32] Significant improvement in sensitivity was found in routine screening following implementation of rapid prescreening and 100% rapid review as methods of internal quality control. Sensitivity increased 24% and 15% for rapid prescreening and 100% rapid review, respectively, in detecting abnormalities as severe as ASC-US or worse.…”

“…4,7,24,29,33 Rates of false-negative results of 1.80% and 1.14% identified by rapid prescreening and 100% rapid review, respectively, were consistent with those reported from other studies, in which the rate of false-negative results ranged from 0.0% to 9.8% with rapid prescreening and from 1.07% to 33.1% with 100% rapid review. 9,15,20,28,[34][35][36][37][38] What, then, would explain that one method is more sensitive than the other despite both methods using the same rapid-screening technique? Why was sensitivity higher in some studies evaluating the 100% rapid review method compared with others that evaluated the same technique?…”

“…[2][3][4][5][6][7][8][9] Without doubt, the most rigorous method of avoiding screening errors and consequently monitoring the quality of routine cytology in laboratories is the repeat screening of all smears defined as negative in routine screening. Unfortunately, there are many problems associated with this method, including the time required to screen all negative smears in duplicate.…”

“…As shown in various studies, it is possible to use abnormal cases identified both by rapid prescreening and by routine screening to monitor the performance of professionals in the daily routine of cytology laboratories. 6,9,20,[22][23][24][25] Nonetheless, it is only in Canada and the United Kingdom that this method is being routinely used. 4,25,26 Finally, the high rates of false-negatives constitute one of the principal problems faced by cytology laboratories.…”

Changing the cytology laboratory information system to improve cytology performance

“…This does not involve "rapid" prescreening, although there are tremendous advantages to that technique. [12][13][14][15] What we are proposing is that a random percentage of the laboratory's workload is prescreened in the usual fashion by cytotechnologists to identify abnormal cases, but no marks are made on the slides. Instead, the cytotechnologist goes to the LIS and enters in a prescreen diagnosis that then remains hidden until the time the case is signed out.…”