I-Med Claims - Medical Billing Company
icd-10 codes

The History of ICD-10 Codes in the U.S. Medical Billing and Coding


Definition of ICD-10 codes

The ICD (International Classification of Diseases) is considered to be an entire spectrum of codes, used to classify diseases according to our anatomy. It includes the category of diseases, their etiology, location, and laterality along with the space to include multiple extensions as well. As opposed to the ICD-9 CM codes, the ICD-10 CM is greater in magnitude and much more specific. As a result, the medical coding in the ICD-10 regime becomes much more nuanced and capable of providing better details of the healthcare service to the insurance providers. 

Importance of medical coding in the billing industry

The billing industry in the United States has gradually evolved over the past few decades and become a major success as compared to other medical billing and coding systems throughout the world. This is primarily because of the advancements in medical coding made by the United States—first by introducing the ICD-9 codes and then replacing them with the detailed ICD-10 codes. This evolution proved to be a major contributor to the overall effectiveness of the medical billing and coding industry, and physicians are now expecting the complete implementation of ICD-11 Coding in the United States as well. 

Predecessors of ICD-10

ICD-9 codes

Introduction and limitations

According to Health Information Associates, the ICD-9 Coding System has its origins in 17th-century England. It is said that all statistical data regarding healthcare was collected in the London Bills of Mortality and arranged appropriately in the form of numerical code. The idea was to utilize these codes in order to figure out the most frequent causes of death at the time. 

With time, these codes started to provide utility to the healthcare sector and became a convenient way for healthcare professionals to classify diseases. After a couple of centuries, such classification was added to the International List of Causes of Death published by the World Health Organization (WHO) in order to track world health trends. 

Evolution of ICD-9 codes

Once the WHO, in 1937, established a classification regime for diseases, the United States also adopted a similar classification that required further detailing with time. After introducing multiple preliminary and basic versions of this classification, the U.S. healthcare industry finally witnessed the entry of the ICD-9 coding mechanism in the 1970s. 

Clinical Modification (CM) and Procedure Coding System (PCS)


The ICD Codes are split between two major categories namely ICD-10CM and ICD-10PCS. The former codes are used for diagnosis coding while the latter codes are used for inpatient procedure coding for a specific hospital in-patient setting. As a result, the ICD-10 coding system becomes much more perplexing and adds value to the overall utility of the codes used for the classification of diseases in the United States. 

Development and implementation

Believe it or not, the ICD-9 coding systems are almost 50 years old, and established way back in the 1970s. Once the US government implemented and streamlined a proper coding system after WWII, the coding system witnessed repeated revisions and finally ended up with a proper classification that has catered to the U.S. healthcare system for approximately 50 years. However, with the advancements in technology, and the updates to the healthcare systems, the billers and coders required greater accuracy and detail for classifying diseases. Hence, talks were initiated to update the ICD-9 codes and make them more nuanced and detailed in 2015. 

Development and Implementation of ICD-10

Need for an updated coding system

The ICD-9-CM codes were approximately 14000 in total and were only used to describe categories and broader nuances of diseases. This meant that a new system was needed that had much more utility when it came to classifying diseases and provided billers with a bigger canvas for medical billing and coding. As a result, the U.S. Healthcare System saw the introduction of the ICD-10 CM and PCS combination which included over 68000 codes, providing the healthcare sector with a more specific and much more accurate system for medical billing and coding. 

International Classification of Diseases, Tenth Revision (ICD-10)

Overview of ICD-10

Introduced in the year 2015, the ICD-10 codes were introduced as a part of a new medical billing and coding regime in the United States. This new regime tried to cater to the various gaps and discrepancies in the ICD-9 codes and ended up with an advanced version known as the ICD-10 coding system. This new coding system provided billers with wider canvas when it came to classifying diseases and introducing more detail and accuracy into the system. 

Differences between ICD-9 and ICD-10

Well, for starters, the ICD-9 system was a much older and widely used system that covered the entire United States for the past several decades. However, it has a limited number of codes ranging from 13,000-14000 ICD-9 CM codes. On the other hand, the ICD-10 coding mechanism has been introduced almost 8 years ago and is being accepted by the entire healthcare infrastructure in the United States. 

Here is a table that appropriately demonstrates the differences between ICD-9 and ICD-10 coding manuals:

AspectICD-9 CM CodingICD-10 PCS and CM Coding
StructureNumeric coding system (3-5 digits)Alphanumeric coding system (3-7 characters)
Level of DetailLess detailed and specificGreater level of detail and specificity
Code ExpansionLimited number of codesExpanded number of codes
Anatomy CoverageBasic coverage of anatomical locationsComprehensive coverage of anatomical locations
Combination CodesRarely usedFrequent use of combination codes
LateralityLimited options for specifying lateralityDetailed options for specifying laterality
Code FormatSingle code for diagnosis or procedureSeparate codes for diagnosis and procedure
Implementation TimelineUsed until September 30, 2015Implemented since October 1, 2015
Worldwide AdoptionWidely used in the United StatesWidely adopted globally

Benefits and Impact of ICD-10

Improved clinical documentation

With an advanced ICD-10 coding manual, the clinical documentation in nursing homes, physician practices, and hospitals has witnessed a massive improvement. The scope increased and widened for medical billers to document clinical practices and procedures. This gave high leverage and space to such practices who were looking to improve their credentialing and enrollment, along with a greater credibility in the industry. 

Enhanced accuracy in coding and billing

With a more detailed coding system, the medical practices in the United States could now have more accuracy in their billing and coding. As a result, claim denial and other liabilities were greatly reduced and high revenue collections and reimbursements were now being ensured. Therefore, the overall financial impact of the new ICD-10 coding for physicians was quite lucrative and provide considerable leeway. 

Expanded code set for increased specificity

With the rise of technology and more research went into the healthcare sector. The details for multiple healthcare services along with the classification of diseases became much more detailed, but requires more specificity. This is where ICD-10 provided healthcare practices with a framework where their can now use a detailed coding mechanism, allowing them to code up to 7 digits as opposed to the 5-digit ICD-9 CM. 

Better tracking of public health data

With a detailed coding manual for healthcare in the United States, it became much more convenient for the authorities to track public health data. The era of COVID-19 was a predicament that tested the limits of this coding manual. For instance, there were multiple cases were a patient was suffering from a chronic illness and was also diagnosed for COVID as well. Now, the test here was for the authorities to track how many people died solely from the impact of the virus and how many people died because their already chronic illness was exacerbated because of the virus. For further details, you can click here to read more. 

Implications for healthcare providers and payers

Healthcare providers who are looking to grapple with the new ICD-10 coding manual, and the upcoming ICD-11, should have these points in mind:
– They should consider outsourcing their medical billing and coding to a professional medical billing company considering the time-taking nature of the task. 

-They should have a plan in mind to cater to the growing patient inflows in the healthcare sector and provide medical billers and coders with capacity building and training. 

-They should establish strong medical billing teams who can help them with their revenue collection and its accuracy in the future as well. 


To sum it up, one can claim the ICD-10 codes to be a masterpiece in the contemporary healthcare sector. This coding manual has developed over time, but it has a solid history to back its success in the U.S. healthcare sector. This is why it has been able to make strides in the industry and provide physicians in the United States with a much more detailed and wholesome alternative to the decades-old ICD-19 coding manual that had its limitations. However, healthcare experts are now expecting a much more effective ICD-11 version in the upcoming times and we will provide you with an analysis of that system as well. So stay intact!

Schedule an appointment