Normal mammograms and the practice of obtaining previous mammograms: usefulness and costs

To determine the usefulness and cost of acquiring and comparing mammograms previously obtained at a different facility with normal mammograms.

Comparison mammographic reports obtained within 52 months in 1,297 consecutive women (aged 33-82 years; mean age, 53 years) were retrospectively reviewed. Mammograms in which a normal interpretation was altered after comparison were reviewed. The clinical importance and the cost of obtaining previous mammograms were determined.

Initially, interpretation was normal in 756 (58%) comparison mammograms and abnormal in 541 (42%). Of the 756 normal mammograms, 197 (26%) were not compared with previous mammograms. Of the remaining 559, 551 (98%) had no change. In eight of the 559 (1%), the original interpretation was altered. Seven of these eight mammograms were available for review: In one, a developing density was detected; in three, differences were attributable to technique; and in three, radiologists had different interpretations. No malignancies were detected. The average labor and postage cost was $21.49.

Considering the cost and low diagnostic yield, obtaining previous mammograms is of limited usefulness.