Contrast media adverse reactions: occurrence, recurrence, and distribution patterns.

The second phase of the survey of adverse reactions to contrast media was based on 4,120 case reports and involved the collaboration of radiologists in 45 institutions. It was directed primarily to a study of the distribution patterns of adverse reactions and the likelihood of recurrence of the same reaction on repetition of the examination. It was found that major life-threatening reactions involving the respiratory system are usually accompanied by minor or less serious reactions, while those involving the cardiovascular system are accompanied by the more serious reactions. Major life-threatening reactions do not usually recur on reexamination, while minor reactions tend to be repeated more often.