ICD-9-CM only has one excludes note. The ICD-9-CM Official Guidelines for Coding and Reporting state that an excludes note under a code indicates that the terms excluded from the code are to be coded elsewhere. An excludes note in ICD-9-CM could mean that you should not use a particular code for a particular condition. For example, reporting a congenital condition with an acquired form of the same condition. Malaria is one condition that can be congenital or acquired. Both the acquired form of the disease (ICD-9-CM category 084) and the congenital form (code 771.2) have excludes notes identifying that the codes should not be assigned together because they are considered mutually exclusive. In ICD-9-CM, an excludes note can also mean that a condition is not included in a particular code. In those cases, you should assign both codes (if applicable) when the patient has both conditions at the same time. For example, a patient may have a closed fracture of the shaft of the tibia (code 823.20) and a Pott’s fracture of the ankle (code 824.4). There is an excludes note under fractures of the tibia and fibula, specifying that Pott’s fractures, among others, are excluded. However a patient could indeed have both fractures, so you would need to assign both codes.
Both these circumstances are also covered in ICD-10-CM but with two different notes thereby lessening the ambiguity and potential for confusion. The two types of excludes notes in ICD-10-CM have a different definition for use. In contrast to ICD-9-CM coding, the ICD-10-CM guidelines are clearly distinguished to eliminate confusion as to the meaning of the exclusion. ICD-10-CM Draft Official Guidelines for Coding and Reporting 2013 defines Excludes Notes as follows: Excludes 1 A type 1 Excludes note is a pure excludes note. It means "NOT CODED HERE!” An ICD-10 Excludes 1 note indicates that the code excluded should never be used at the same time as the code above the Excludes 1 note. An Excludes 1 is used when two conditions cannot occur together, such as a congenital form versus an acquired form of the same condition. Excludes 2 A type 2 Excludes note represents "Not included here". An ICD-10 Excludes 2 note indicates that the condition excluded is not part of the condition represented by the code, but a patient may have both conditions at the same time. When an Excludes 2 note appears under a code, it is acceptable to use both the code and the excluded code together, when appropriate.