Double read screening mammograms: the use of a third reader to arbitrate on disagreements

Screening mammograms from a county wide breast screening programme were double read by any 2 from a team of 3 radiologists. There were 398 cases where the 2 readers disagreed. The third radiologist was asked to arbitrate on these. The third reader recalled 49% and returned the other 51% to normal screening. From the 196 recalled for assessment, 9 underwent histological examination and from these, 4 malignant lesions were found. From the 202 sent to normal screening, one true interval cancer has occurred during 3 years of follow-up. Double reading mammography increases the sensitivity of screening. If this is combined with arbitration in disagreements the number of unnecessary recalls is reduced.