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Avoid Common ICD10CM Coding Mistakes

As we begin to discuss the transition to ICD11CM, let us not forget that we are still utilizing the ICD10CM coding manual and all that entails. We need to be sure that we understand how to determine the necessary codes and how to be sure that if there is more than one code, they are properly sequenced. Not to mention that we need to be sure that we are following the guidelines correctly. All of these are the tasks at hand in order to determine the correct codes.

Understand your ICD10CM Coding Manual

The first step to avoid common ICD10CM coding mistakes is to understand your manual. If you are new to coding, look through it and understand the layout. There are different tables and sections that are utilized and you need to know and understand the information contained in these different sections.

Be Aware of Coding Conventions

Next be aware of the coding conventions in ICD10CM. They include instructional notes, abbreviations, cross-reference notes, punctuation marks and certain terms such as “and”, “with”, “without” and “due to”. Once you are aware of these, be sure that you understand the meanings so that you can best apply them. For example, “excludes 1” means “not coded here”. When you see this note, the code excluded should never be used at the same time as the code above the “excludes 1” note. You will typically see this note when two conditions cannot occur together and this means that both codes cannot be used together.


There are two abbreviations in ICD10CM that you will want to become familiar with. These are NEC and NOS. They both have specific meanings and can be quite confusing to new coders. Be sure that you understand what they stand for and that you are familiar with their differences.

Cross-reference Notes

Cross-reference notes also play a big part in ICD10CM coding. When you see words like, “see”, “see also”, “see category” and “see condition”, be sure that you understand their meanings. They are directing you to information that will help you to assign the most specific code possible, so always adhere to their direction when you see them.

Punctuation Marks

The punctuation marks also play a part in assigning the correct ICD10CM codes. You have parentheses, square brackets, and colons. It is important to know the meaning of these and be able to recognize them and appropriately assign the correct codes based on them.

Relational Terms

The last of these are the relational terms. These are “and”, “with”, “in”, and “due to”. These all have different meanings but basically direct you towards assigning the correct number of codes. It can also link two illnesses together to help you to assign the most specific code possible. For example, Type 2 diabetes mellitus with diabetic chronic kidney disease. You see the word “with” so that is an indicator that once you locate the main term of the major illness, which would be Type 2 diabetes, you look for the word “with” underneath it to add the chronic kidney disease to the code.

ICD10CM coding is not confusing, but many new coders do struggle with it mainly due to the magnitude of information that the manual contains. These are just a few of the basic steps to get you started and more familiar with the manual. If you know how to navigate the manual, you are one step closer to successful ICD10CM coding.


Curious about what is included in and covered in Blackstone’s online Medical Billing and Coding course? Check out the full syllabus, program goals and objectives, and included course materials here!


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