Proficiency Testing Improvement Act of 2005 - Prohibits the Secretary of Health and Human Services from conducting laboratory proficiency testing of individuals involved in screening or interpreting cytological preparations for one year. Requires the Secretary to revise such proficiency testing before resuming it in order to: (1) reflect the collaborative clinical decision-making of laboratory personnel involved; (2) revise grading or scoring criteria to reflect current practice guidelines; (3) provide for such testing to be conducted no more than every two years; and (4) make such other revisions as necessary to reflect changes in laboratory operations and practices since the standards were promulgated.