Studies included in the meta-analysis
| Lead author | Year | Platform | Total number of cervical cytology smears | Number of unsatisfactory smears | Percentage of unsatisfactory smears | Location of study |
| Zhao et al9 | 2011 | TP | 972 | 2 | 1.5 | China |
| Zhao et al9 | 2011 | SP | 1033 | 15 | 0.2 | China |
| Kitchener et al13 | 2011 | TP | 23 436 | 456 | 2.0 | UK |
| Kitchener et al13 | 2011 | SP | 22 145 | 354 | 1.6 | UK |
| Narine and Young14 | Unpublished | TP | 58 973 | 1250 | 2.1 | UK |
| Narine and Young14 | Unpublished | SP | 27 738 | 327 | 1.2 | UK |
| Nance17 | 2007 | TP | 88 575 | 567 | 0.6 | USA |
| Nance17 | 2007 | SP | 92 875 | 158 | 0.2 | USA |
SP, SurePath; TP, ThinPrep.