Human papillomavirus genotype detection from archival papanicolaou-stained cervical tests

Archival Papanicolaou (Pap)-stained cervical cytology tests may be the only source of a clinical sample for the evaluation of previous human papillomavirus (HPV) infection. Pap tests are ideal because the majority of women in countries with comprehensive screening programs would have had several collected and stored.

In the current study, HPV detection and genotyping were compared in samples collected from a conventionally fixed Pap test with those collected using an endocervical brush and collected in PreservCyt (liquid-based) in 87 women undergoing management for a high-grade Pap test abnormality. Cytology slides were scanned to create high-resolution digital images before the removal of cells because the DNA extraction process resulted in the destruction of the cells from the original sample.

All previously identified high-grade abnormalities on the Pap tests were detectable on the digital images. β-globin was detected in all extracted Pap tests, indicating the presence of recoverable, amplifiable DNA. A total of 62 (71.3%) and 59 (67.8%) tests were found to have high-risk (HR) HPV detected on PreservCyt and fixed Pap test slides, respectively, with >87% concordance for the detection of HR HPV genotypes. Complete HPV genotyping concordance was observed in 62% and was partial in 26% of sample pairs, with very good agreement for HPV types 16 and 18 (κ = 0.850 and 0.903, respectively). Only 1 Pap test slide was found to be positive whereas the PreservCyt had no detectable HPV DNA, demonstrating a low false-positive rate (1%).

The results of the current study confirm that imaging and subsequent HPV detection and genotyping in archival cervical smears can offer accuracy in HPV detection that is comparable to endocervical brush-collected PreservCyt samples.