Pap test discrepancies and follow-up histology: Who's right and does it help to know?

Papanicolaou (Pap) test discrepancy rates between cytotechnologists (CTs) and cytopathologists (CPs) are often kept to evaluate the performance of individual CTs. This is based on the unproven assumption that the CP's diagnoses are more likely to be correct. We investigated this assumption using data from our discrepancy files and comparing them to follow-up histology. All Pap test discrepancies were noted between January 1, 2001-December 31, 2001. Surgical pathology files were then searched for follow-up histology within 9 mo of the Pap test. Histologic diagnoses were compared with the previous CT and CP diagnoses, and then judged regarding accuracy. In total, 63,376 Pap tests were evaluated between January 1, 2001-December 31, 2001. There were 795 discrepancies throughout this period (1.25%). One hundred and sixty-six cases with discrepancies had follow-up histology within 9 mo of the Pap test (20.9%). Of downgraded cases (103), CPs were more correct in 51 cases (49.5%), whereas CTs were more correct in 52 cases (50.5%). Of upgraded cases (63), CPs were more correct in 19 cases (30.2%), whereas CTs were more correct in 44 cases (69.8%). Our results suggest that CPs are not more likely to be correct than CTs when there is a discrepancy with the diagnosis of a Pap test, especially when CPs upgrade CT diagnoses. This suggests that discrepancy data may be helpful for evaluating the performance of both CPs and CTs. It may also be of educational use for both CPs and CTs to know the follow-up histology in these cases.