The Difference between ICD 9 and ICD 10 Codes

The Difference between ICD 9 and ICD 10 Codes

ICD 9 codes were replaced by ICD 10 on October 01, 2015 as they had some inherent issues which were addressed and rectified in ICD 10.

However, it is important to understand that ICD 10 codes are not merely ICD 9 codes that have been increased in numbers or volume; ICD 10 codes with changes in terminology and providing far more details are definitely more complex than ICD 9 codes.

So, what is the difference between ICD 9 and ICD 10 codes? And what is ICD 9 and ICD 10? We are going to discuss all these in the following article. Let’s dive right in.

The History of the ICD Standard

ICD stands for the International Classification of Diseases. ICD 9 is the ninth revision and was used worldwide, with countries like the US having their own implementation.

Why is the ICD 9 and ICD 10 important?

The ICD standard ensures consistency in how doctors record diagnoses and symptoms
The ICD standard ensures consistency in how doctors record diagnoses and symptoms

The standardized codes improve consistency among physicians as they record patient symptoms and diagnoses. These codes are used in clinical research and payer claim reimbursements.


Normally, ICD codes are entered into a patient’s electronic health records. The ICD 9 was ratified in 1975 at the WHO conference and for a long time, was the basis on which the American healthcare payments are based.

ICD 9 has been stable which explains why a slew of other practices and standards developed around it. Nonetheless, many countries migrated to using of ICD 10, which has more granularity and data than ICD 9.

ICD 10 was released in the 1990s and until 2015, the US was left behind in terms of research capabilities because of delayed implementation.

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In 2008, an announcement from CMS stated that the US would now start using the ICD 10 CM, which is the American version of the ICD 10 implementation. Since insurance companies adhere to the CMS guidelines, ICD 10 is the national standard.

Reasons for the Failure to Implement the ICD 10 Nationwide and its Consequences

The reason why ICD 10 had a slow nationwide implementation is that of technical and political complications surrounding the issue. This is why its implementation was been delayed a number of times.

One of the reasons healthcare facilities stuck to the ICD 9 standard for a while was because it had a less rigorous documentation than ICD 9.

I’m not going to lie to you…

The implementation of the ICD 9 coincided with major changes in the healthcare system, such as the adoption of electronic health records, the establishment of national health information exchanges and data-intensive accountable care organizations.

As such, moving from the ICD 9 to the ICD 10 standard, involved major changes in hospital workflows. For starters, it required physicians to create more patient documentation upfront that would be fully reimbursed months or weeks later.

What are the differences between ICD 9 and ICD 10?

ICD 9 vs ICD 10 Diagnosis Codes

Let us look at the basic comparison between the features of ICD 9 and ICD 10 diagnosis codes.

ICD 9 ICD 10
Contains around 13,000 codes Contains around 68,000 codes
Code length is 3 to 5 characters Code length is 3 to 7 characters
Digit one can be either alpha or numeric First digit is always alpha
Addition of new codes has limitations More flexibility in adding new codes
Codes lack details Codes indicate more details, are more specific
Codes lack laterality Codes have laterality
  • Unlike the diagnosis code set of ICD 9, the alpha characters in the ICD 10 diagnosis code set are not case sensitive.
  • ICD 10 diagnosis code set features more characters, thus providing better details regarding a disease, severity of the disease and more precise anatomic site. Characters 1 to 3 indicate the category.
  • Characters 4 to 6 indicate the etiology, disease severity, anatomic site and any other clinical details. The 7th character is an extension that provides additional information.
ICD 10 offers a more robust way of documenting diseases and diagnoses than ICD 9
ICD 10 offers a more robust way of documenting diseases and diagnoses than ICD 9
  • ICD 10 diagnosis codes expand and allow the use of combination codes. This helps in expressing multiple elements using a single code. ICD 9 diagnosis code sets did not have this flexibility.

The best part?

  • Since ICD 10 diagnosis code sets are very specific, they help in reducing requests for documentation and denied claims.

ICD 9 vs ICD 10 Procedure Codes

The following are the differences between ICD 9 and ICD 10 procedure codes.

ICD 9 ICD 10
Featured around 3000 codes Features around 87000 codes
Code length was 3 to 4 characters Code length is 7 characters
Codes were always numeric in character Codes are alpha-numeric in character
Featured body parts in generic terms Features detailed description of anatomical parts
Procedure definition lacked precision Provides detailed procedure and other details
Procedural approach lacked details Provides detailed approach for procedures
Methodology descriptions lacked details Provides detailed methodology descriptions
  • Similar to the diagnosis code set, the alpha characters in ICD 10 code sets are not case-sensitive.
  • The letters “O” and “I” are not in the code set. This is to ensure there is no confusion between the letters and the number 0 and 1.
  • The 7 characters in the procedure code set help in providing very precise details. The first character identifies the section name. The second character identifies the system of the body. The third character identifies the basic operation.
  • The fourth character identifies the part of the body. The fifth character indicates the approach. The sixth character identifies the device and the seventh character indicates the qualifier.

Here’s the bottom line:

  • ICD 9 was based on outdated technology and was unable to reflect new equipment or procedures. ICD 10, on the other hand, allows better integration with current technology. It also allows for better flexibility to create and add new codes.

Why the Change from ICD 9 to ICD 10

The periodic revisions in the ICD implementation reflect the changes in the medical sector. For example, the US has used ICD 9 since 1979 although the implementation is not robust enough to cater for future healthcare needs.

Here’s why this is important…

ICD 9 content is now clinically inaccurate and contains a limited data set about the medical condition patients suffer from as well as procedures given to inpatients.

Moreover, the codes in ICD 9 are less, meaning that the framework has many restrictions.

Also, America cannot directly compare the morbidity diagnosis data to that ofthe state and national level. This is because mortality data has already transitioned to the use of ICD 10.

Majority of the developed countries have moved to use the ICD 10 standard. As such, it is impossible for the US to compare its morbidity data with that from other countries.

ICD 10 and ICD 11 Release and Implementation Schedule

ICD 10 was scheduled for launch in 1st October 2015 following a delay of its implementation by Congress.

There is a possibility that some sectors of the US healthcare such as the long-term care facilities, employer-based payers, prison medical systems and nursing homes will continue using a hybrid of ICD 9/ICD 10.

What are the Advantages of Switching to an ICD 10 Standard?

For starters, ICD 10 is better at tracking healthcare conditions, especially complications and patient anatomy. ICD 10 offers improved data for epidemiological research, such as co-morbidities and severity of illness.

ICD 10 is great for measuring outcomes and care provided to patients. As such, it is great in making clinical decisions, identifying abuse and fraud and processing claims.

The deadline for transitioning to ICD 10 was 1st October 2015, after which users would transition to the new code sets. For secondary users, the data they receive from hospitals from 2015 was coded in ICD 10.

ICD 10 offers improved quality of data. It also offers more granularity than ICD 9. ICD 10 also offers better data that helps in tracking and measuring health care utilization and the quality of patient accounts.

And that’s not all…

ICD 10 contains a greater level of detail in terms of severity, complexity, and laterality. This will allow for a higher precision identification and tracking of certain conditions. ICD 10 offers better terminology and classification of diseases.

ICD 10 also offers more detail than ICD 9 with regards to poisonings, injuries and external causes. It also records how and where the injuries happened. ICD 10 contains more extensions that provide extra information for the majority of the injury codes.

Moreover, ICD 10 contains new concepts that were not contained in ICD 9 like blood type, dosing, alcohol level and the Glasgow Coma Scale. In ICD 10, postoperative codes have been expanded to distinguish between post-procedural and intraoperative complications.


In this article, we have looked at the difference between ICD9 and ICD10.

As you can see, there are major differences between ICD 9 and ICD 10. To ensure that your practice runs smoothly and profitably, it is important that your medical billing and coding processes are timely and error-free.

However, the time and quantity of work required to keep up with the medical billing process can take you away from treating your patients.

The transition from ICD 9 to ICD 10 can be overwhelming as the number of codes has increased drastically with even more codes being added from time to time. In addition, there are the changing insurance payer guidelines.

Our certified ICD 10 coders are well versed with medical billing and coding requirements and constantly upgrade themselves to the new requirements. Contact us for all billing and coding requirements and ensure your peace of mind.


  1. ICD-9 and ICD-10 Chapter Guideline Comparisons. (2018). Retrieved June 30, 2018, from
  2. International Classification of Diseases, (ICD-10-CM/PCS) Transition – Background. (2018). Retrieved June 30, 2018, from
  3. (2016, May 01). Basic Differences between ICD 9 and ICD 10. Retrieved June 30, 2018, from
  4. The Differences between ICD 9 and ICD 10. (2015, October). Retrieved June 30, 2018, from

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