1. One of the main obstacles to the reliable detection of human papillomavirus in cervical intraepithelial neoplasia is that a minute quantity of infected tissue is often all that is available.
2. In this work, proteinase K-phenol-chloroform-treated sections of frozen cervical biopsies were split in two. Half of the material was precipitated by ethanol in the presence of glycogen, and in the remaining half glycogen was absent.
3. On average a 15-fold increase in total DNA yield was obtained with glycogen. As a result, in 63 cases analysed by PCR for human papillomavirus type 16, we were able to detect nearly 20% more positive samples when glycogen was used.
4. The implications of the improved accuracy of diagnosis are that women requiring a closer follow-up can be identified, and conversely rescreening intervals can be extended for those testing negative for oncogenic human papillomavirus types with more confidence than in the past.