Objective: To determine the clinical significance in normal Pap smears of HPV detection as determined by Hybrid Capture (HC) and in situ hybridization analyses.
Study design: We studied 135 consecutive Pap smears as well as 46 other smears from high-risk patients each initially diagnosed as within normal limits.
Results: The 135 "normal" Pap smears were rescreened, and 6 (4%) where found to be either ASCUS or SIL. In the remaining 129 cases, HPV DNA was detected in 0% and 9%, respectively, using in situ hybridization and HC I. Upon rescreening the high-risk patients, nine (20%) were reclassified as having SIL/ASCUS; each was in situ hybridization positive, and eight were HC positive; six (67%) of these women developed SIL on follow-up. In the 37 Pap smears in high-risk women still within normal limits after manual rescreening, HPV was detected in 2% by in situ hybridization and 46% by HC; 6% of the HC-positive women developed SIL on follow-up.
Conclusion: In situ hybridization rarely detects HPV in Pap smears diagnosed as within normal limits after manual rescreening. In situ hybridization is very effective in detecting rare, atypical cells in Pap smears diagnosed as within normal limits and, in a high-risk population, is predictive of SIL on clinical follow-up.