==Comparison==
A report should include the date(s) of any images used for comparison. Comparison (or mention thereof) is not needed if absence of pathology is clear even without it. For short reports, the date (in local date format) can be integrated in a sentence if the form layout allows, such as ''"Compared to the CT July 3, 2018, the consolidation..."''. Where comparisons are expected for multiple findings in an exam, the comparison should be mentioned separately at the beginning of the report, such as ''"Comparison: July 3, 2018"'', each item can be described similar to "compared to earlier...".
The clinical context for a previous exam may be mentioned in order to put relevance to similar findings. For example, radiodense fat around the gallbladder on both a previous and a current CT is more likely a sign of cholecystitis if there were clinical signs of it on the previous occasion.
==Certainty==