# Differences between ICD 9 ICD 10



## Chunduri (Feb 12, 2014)

Hi,

Can anyone share a source / list of the major and crucial differences between ICD-9 and ICD-10 especially in case of *rules and conventions*. The differences that are needed to be considered while Billing/Coding(not the basics differences). 


Some of the examples: 

Principle diagnosis sequencing rules in ICD 9 and 10 (if any)
Laboratory Confirmation Diagnosis coding rules(If any)

similar type of list where we can clearly distinguish between 2 editions. I hope this will be helpful to everyone out here.


Thanks in advance


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## hjchamas (Feb 12, 2014)

I was unable to find a list of the comparisons or differences. However, I did find the rules and guidelines for ICD-10. The CMS website has a wealth of information on the subject and perhaps I just wasn't querying the correct information.

Here's what I found:
http://www.cms.gov/Medicare/Coding/ICD10/Downloads/pcs_2013_guidelines.pdf


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## Chunduri (Feb 12, 2014)

Thanks for the response. but I already have those guides with me. 
I would like to find out the Major and Crucial differences or distinguishing guidelines/concepts between ICD 9 and 10


Example.For Combination codes(in ICD 9) we use 2 different codes but that is expanded in the ICD 10(only one code describes full)...  Similar type of differences if any. 




Appreciate your help


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## mitchellde (Feb 12, 2014)

the differences you want are contained in the guidelines.  I looked at the ICD-9 CM guidelines and compared them to the ICD-10 CM guidelines page for page, chapter for chapter, that is how I then determined where the major differences were as far as which code is first listed and which is secondary and when codes must be paired.  In addition there are chapter specific instructions which requires that read the chapter beginnings as well as sub chapter instructions.  I looked at the entire book from the first page to the last before I developed my ICD-10 CM presentation.
Also be sure you are looking at ICD-10 CM information and not ICD-10 , these are different code sets and have different rules.


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