Post Oct. 1, 2015, there has been a need to return cases for additional information and/or clarification. If an indication does not include a default code, additional information will be required to assign a primary diagnosis code.

The Official Guidelines for Coding and Reporting Section 1.A.18, Default Codes, instructs the following:

A code listed next to a main term in the ICD-10-CM Alphabetic Index is referred to as a default code. The default code represents that condition that is most commonly associated with the main term, or is the unspecified code for the condition. If a condition is documented in a medical record (for example, appendicitis) without any additional information such as acute or chronic, the default code should be assigned.

 To better understand the need for this information, the following Q&A provides some guidelines:

Q:  Why is an indication of "wound" or "laceration" not acceptable to code?
A:   A wound or laceration is a codeable condition only when the site of the wound or laceration is   documented. In ICD-10 there is no default code for an unspecified wound or laceration without documentation of the location.

Q:  Why can’t we use an indication of "congestion" on a chest x-ray? 
A:   Per the alphabetic index of ICD10-CM, the term congestion requires knowing where the congestion is located. Is the congestion in the chest, or lung, or nasal, etc?  Documentation of the site of congestion is needed to assign a primary diagnosis code.

Q:   Nodule is indicated for chest CT, why is additional information needed?
A:   The term "nodule" does not list a default code in the alphabetic index. The anatomic location or type of nodule is required to be able to assign a primary diagnosis.

Q:   Ankle X-ray with an indication of "sprain"?
A:   The anatomic location of the sprain will need to be specified before a primary diagnosis can be assigned.

While certain default codes may have existed previously in ICD-9, ICD-10 may now require documentation of additional specificity regarding the site or anatomic location of the condition.

ICD-10-CM Diagnosis Codebook – 2016
ICD-10-CM Official Guidelines for Coding and Reporting 2016