Background Misinterpretation of radiological examinations is an important contributing factor to diagnostic errors. Consultant radiologists in Norwegian hospitals frequently request second reads by colleagues in real time. Our objective was to estimate the frequency of clinically important changes to radiology reports produced by these prospectively obtained double readings.

Methods We retrospectively compared the preliminary and final reports from 1071 consecutive double-read abdominal CT examinations of surgical patients at five public hospitals in Norway. Experienced gastrointestinal surgeons rated the clinical importance of changes from the preliminary to final report. The severity of the radiological findings in clinically important changes was classified as increased, unchanged or decreased.

Results Changes were classified as clinically important in 146 of 1071 reports (14%). Changes to 3 reports (0.3%) were critical (demanding immediate action), 35 (3%) were major (implying a change in treatment) and 108 (10%) were intermediate (requiring further investigations). The severity of the radiological findings was increased in 118 (81%) of the clinically important changes. Important changes were made less frequently when abdominal radiologists were first readers, more frequently when they were second readers, and more frequently to urgent examinations.

Conclusion A 14% rate of clinically important changes made during double reading may justify quality assurance of radiological interpretation. Using expert second readers and a targeted selection of urgent cases and radiologists reading outside their specialty may increase the yield of discrepant cases.