Should liquid-based cytology be performed prior to colposcopy? A comparison of the accuracy, unsatisfactory rates and cost in a tertiary referral setting.

OBJECTIVE

To compare the use of liquid-based cytology (LBC) with conventional cytology (CC) in the assessment cervical intraepithelial neoplasia (CIN) prior to colposcopy.

DESIGN

Retrospective Cohort Study.

METHODS

Liquid-based cytology and CC findings were compared with colposcopic assessment and directed cervical biopsy in terms of sensitivity and specificity for high grade lesions only and for any abnormalities. The degree of correlation was sought. Secondary outcomes were unsatisfactory rate and cost.

RESULTS

A total of 1961 women had colposcopy of whom 528 had cervical biopsy. LBC and CC have similar sensitivity and specificity for both high-grade lesions and any abnormalities. In comparison with cervical biopsy, LBC and CC sensitivity for high-grade disease was 89.1% and 88.6% respectively and for any abnormalities, the sensitivity was 86.6% and 87.0%. Specificity for high-grade disease was 83.1% and 84.7% and for any abnormalities, the specificity was 53.8% and 56.4%. The unsatisfactory rate was significantly lower in LBC 4.38% compared to 1.84% (P < 0.001). However, the use of LBC was associated with an additional cost of A$1496 for each unsatisfactory smear avoided.

CONCLUSION

In high prevalence setting, LBC showed no statistically significant difference in sensitivity and specificity from CC for the detection of CIN. A reduction in unsatisfactory smears was evident, but at significant additional cost.