Excludes1 Note

A type 1 Excludes note is a pure excludes note. It means, “NOT CODED HERE!" An Excludes1 note shows that you should never use the excluded code at the same time as the code above the Excludes1 note. An Excludes1 note is used when 2 conditions can’t occur together, like a congenital form versus an acquired form of the same condition.

The Excludes1 note in this example means that you can’t report the codes under this category describing a congenital form of a disease with the code for the acquired form of the same condition. In this example, code Q21.0, describing congenital ventral septal defect, can’t be reported with I51.0, the code for acquired cardiac septal defect.

We’ll discuss an Excludes1 note exception in Lesson 4.