This article continues the multi-part series that highlights the key differences in the coding guidelines cited in the ICD-10-CM version of the Official Guidelines for Coding and Reporting (OG10) as opposed to the ICD-9-CM version (OG9).

Section I: Conventions, general coding guidelines and chapter specific guidelines

C: Chapter-Specific Coding Guidelines
As stated in previous articles, OG10 contains 21 chapters within Section IC (compared to the 19 chapters in OG09). Key changes (additions, revisions, or deletions) made in chapters 6 through 12 of this section are provided below.

Chapter 6: Diseases of the Nervous System and Sense Organs (G00-G99)
Because of the ICD-10-CM notoriety for specificity, a new instruction for coding dominant and nondominant sides have been added to the nervous system chapter. If documentation is not specific as to dominant or nondominant when coding hemiplegia or monoplegia and the classification system does not indicate a default, the default should be dominant. For ambidextrous patients, the default should also be dominant.

Chapter 7: Diseases of Eye and Adnexa (H00-H59)
Although this is a new chapter; it does not provide any specific guidance and is reserved for future expansion.

Chapter 8: Diseases of Ear and Mastoid Process (H60-H95)
As with Chapter 7, this is a new chapter that does not provide specific guidance and is reserved for future expansion.

Chapter 9: Diseases of the Circulatory System (I00-I99)
The revised instruction for coders in chapter 9 (chapter 7 in OG09) is related to the combination code for atherosclerotic heart disease with angina pectoris. When using one of these combination codes, it is not necessary to use an additional code for angina pectoris. A causal relationship may be assumed in a patient with both atherosclerosis and angina pectoris, unless the documentation indicates the angina is due to something other than atherosclerosis.

The next notable change is indicated for an admission for a subsequent acute myocardial infarction within 4 weeks of the initial acute myocardial infarction (AMI). This is a change from previous Coding Clinic guidance of 8 weeks.

Chapter 10: Diseases of Respiratory System (J00-J99)
The change for coders in chapter 10 (chapter 8 in OG09) is the elimination of the detailed instruction behind coding chronic obstructive pulmonary disease (COPD) with asthma in sub-sections for conditions that comprise COPD and asthma, overlapping nature, and acute exacerbation vs. status asthmaticus, COPD and bronchitis. This leaves only one instruction for the coding of acute exacerbation of chronic obstructive bronchitis and asthma, an instruction that is consistent with the OG09.

Chapter 11: Diseases of the Digestive System (K00-K94)
Consistent with Chapter 9-Diseases of the Digestive System in OG09, this chapter continues to be reserved for future guideline expansion.

Chapter 12: Diseases of the Skin and Subcutaneous Tissue (L00-L99)
The key change in this chapter is the inclusion of a combination code for pressure ulcers that identifies the site with the stage.

Next month: This series will continue with a section-by-section comparison of the key differences between the OG9 and OG10.


Carol Spencer (cspencer@medlearn.com) is a senior health care consultant with Medical Learning Inc. (MedLearn), St. Paul, MN.