The Diagnostic Accuracy of Frozen Section Compared to Permanent Section: A Single Center Study in Iran

Background:The diagnostic accuracy of frozen section as an important source of information in surgical pathology is important not only in the management of surgical patients but also as a measure of quality control in surgical pathology. In this study, we evaluated the diagnostic accuracy of frozen sections over a 6-year period in a teaching hospital in Iran. Methods: We retrospectively reviewed frozen sections performed in the Pathology Department of Taleghani Hospital (Shahid Beheshti University of Medical Sciences), Tehran, Iran from 2007 to 2013. The results were compared to the permanent sections to evaluate diagnostic accuracy, sensitivity and specificity, of frozen section test. Discordant cases were reassessed to find the reasons for discrepancy. Results: A total of 306 frozen section specimens from 176 surgical cases were evaluated. In eleven specimens (3.59%) the diagnoses were deferred. Of the remaining 295 specimens, 6 (2.03%) were discordant and 289 (97.96%) were concordant to permanent diagnoses. Specimens were primarily from the head & neck, thyroid, ovary, parathyroid and lymph nodes. The overall sensitivity, specificity, positive predictive value and negative predictive value of the frozen section compared to permanent section (as gold standard) were 92.95%, 99.55%, 98.50% and 97.80% respectively. Of the 6 discordant diagnoses, two (33.3%) were due to sampling error and four (66.6%) were due to interpretative errors. Conclusion: Frozen section is an accurate and valuable test and can be relied on in surgical managements. The results of this study also confirm that the accuracy of frozen section diagnosis in our institution compares well with internationally published rates.