Final answer:
In medical coding, the addition of a modifier to a procedure code indicates that the procedure was extensive, unusual, or required an assistant.
Step-by-step explanation:
When a procedure is extensive, unusual, or requires an assistant, a modifier would typically be added to the procedure code. In medical billing and coding, modifiers are used to provide additional information about a performed procedure. These are two-digit alphanumeric codes that can signify if a procedure was more complex or time-consuming than usual or if an extra professional was needed to assist. For example, modifier -22 indicates that the procedure was more extensive than usually required, and modifier -80 is used when a surgical assistant is necessary.