Purpose: In the adult emergency department of a university hospital, we investigated the frequency of major discrepancies between the preliminary reports by radiology residents and the final reports by certified radiologists. Materials and Methods: Based on CT and MRI scans obtained between December 2016 and November 2019, we selected cases with diagnoses or treatment plans that could be changed due to discrepancies between preliminary and final reports and classified them by the type of discrepancy. We also examined the distributions of the major discrepancies and stratified them by residents’ working time zone, experience, and subspecialty. Results: Based on the 72137 preliminary reports evaluated, 1348 tests (1.9%) showed major discrepancies. Most of the major discrepancies were false negatives (72.0%), followed by misdiagnosis (26.3%) and false positives (1.7%). Acute findings (87.2%) were more common than nonacute findings (12.8%). The major discrepancy rate increased toward the second half of the 24-hour shift, with the highest rate of 2.9% occurring between 2 am and 4 am. The major discrepancy rate did not vary with experience, and it varied from 0.6% to 4.5% for each subspecialty. Conclusion The major discrepancy rate was less than 2%, and it increased with longer working hours during a 24-hour shift.

Purpose: In the adult emergency department of a university hospital, we investigated the frequency of major discrepancies between the preliminary reports by radiology residents and the final reports by certified radiologists. Materials and Methods: Based on CT and MRI scans obtained between December 2016 and November 2019, we selected cases with diagnoses or treatment plans that could be changed due to discrepancies between preliminary and final reports and classified them by the type of discrepancy. We also examined the distributions of the major discrepancies and stratified them by residents’ working time zone, experience, and subspecialty. Results: Based on the 72137 preliminary reports evaluated, 1348 tests (1.9%) showed major discrepancies. Most of the major discrepancies were false negatives (72.0%), followed by misdiagnosis (26.3%) and false positives (1.7%). Acute findings (87.2%) were more common than nonacute findings (12.8%). The major discrepancy rate increased toward the second half of the 24-hour shift, with the highest rate of 2.9% occurring between 2 am and 4 am. The major discrepancy rate did not vary with experience, and it varied from 0.6% to 4.5% for each subspecialty. Conclusion The major discrepancy rate was less than 2%, and it increased with longer working hours during a 24-hour shift.