Liquid compared with conventional cervical cytology: a systematic review and meta-analysis

Obstet Gynecol. 2008 Jan;111(1):167-77. doi: 10.1097/01.AOG.0000296488.85807.b3.


Objective: To compare test performance characteristics of conventional Pap tests and liquid-based cervical cytology samples.

Data sources: Eligible studies, published between 1991 and 2007, were retrieved through PubMed/EmBase searching and completed by consultation of other sources.

Methods of study selection: Studies were selected if a conventional and a liquid-based sample were prepared from the same woman or when one or the other type of sample was taken from a separate but similar cohort. The current systematic review and meta-analysis is restricted to studies where all subjects were submitted to gold standard verification, based on colposcopy and histology of colposcopy-targeted biopsies, allowing computation of absolute and relative test validity for cervical intraepithelial neoplasia grade 2 or worse. Randomized trials were selected as well if all test-positive cases were verified with the same gold standard, allowing computation of the relative sensitivity. Impact of study characteristics on accuracy was assessed by subgroup meta-analyses, meta-regression, and summary receiver operating characteristic curve regression.

Tabulation, integration, and results: The relative sensitivity, pooled from eight studies, with complete gold standard verification and from one randomized clinical trial, did not differ significantly from unity. Also, the specificity, considering high-grade and low-grade squamous intraepithelial lesions as cutoff, was similar in conventional and liquid cytology. However, a lower pooled specificity was found for liquid-based cytology when presence of atypical squamous cells of undetermined significance was the cutoff (ratio 0.91, 95% confidence interval 0.84-0.98). Differences in study characteristics did not explain interstudy heterogeneity.

Conclusion: Liquid-based cervical cytology is neither more sensitive nor more specific for detection of high-grade cervical intraepithelial neoplasia compared with the conventional Pap test.

Publication types

  • Meta-Analysis
  • Research Support, Non-U.S. Gov't
  • Review
  • Systematic Review

MeSH terms

  • Cervical Intraepithelial Neoplasia / diagnosis*
  • Cervical Intraepithelial Neoplasia / pathology
  • Colposcopy
  • Female
  • Humans
  • Mass Screening / methods
  • Randomized Controlled Trials as Topic
  • Sensitivity and Specificity
  • Specimen Handling
  • Uterine Cervical Neoplasms / diagnosis*
  • Uterine Cervical Neoplasms / pathology
  • Vaginal Smears / methods*