Frequently Asked Questions about ICD-10

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We have created this resource in an effort to prepare and train our members for the smooth transition from ICD-9 to ICD-10. As you know this transition is mandatory and the new set of codes are complex, but we are here to guide you through the process! Do you have specific questions about ICD-10? Submit your question below and one of our ICD-10 experts will respond to you as soon as possible. If we think it will be helpful to other members, we'll post the Q&A here.

What is ICD-9?

ICD-9-CM (International Classification of Diseases, 9th edition, Clinical Modifications) is a set of codes used by healthcare providers to indicate diagnosis for all patient encounters. The ICD-9-CM is the HIPAA transaction code set for diagnosis coding.
The roots of current ICD can be traced back to the Bertillon Classification first published in 1893. Starting in 1900, experts met about every 10 years under the auspices of the French government to revise the classifications. The World Health Organization took over responsibility for ICD in 1946 with publication of ICD-6.
Since 1979, ICD-9-CM has been in use. The original intent for the diagnosis codes was for epidemiological and not billing functions, although in the US, the codes are used by payers for billing and reimbursement purposes.
ICD-9 diagnosis codes consist of:  3-5 numeric characters representing illnesses & conditions.
E codes (alpha-numeric) describing external causes of injuries, poisonings, and adverse effects.
V codes describing factors influencing health status and contact with health services.

ICD-9-CM consists of three volumes. Physicians use Volumes 1 and 2 only to assign diagnosis codes. Rather than Volume 3 of the ICD-9-CM codes, physicians use Current Procedural Terminology (CPT) published by the American Medical Association to report medical and surgical procedures and physician service codes. The 3rd Volume of ICD-9-CM is used by Hospitals for reporting inpatient procedures and resource utilization.


Why is the ICD-9-CM coding system being replaced?

The ICD-9-CM coding system has become outdated and obsolete. The 9th revision cannot describe diagnoses accurately with the level of detail needed for the reporting purposes of our health care system. Identifying and capturing health care data is used for tracking trends, analyzing quality, comparing and evaluating outcomes from different treatment methods, and comparing statistics internationally.

Many countries have already moved to ICD-10-CM for both morbidity and mortality statistics since 1994, making diagnosis coding incompatible with the United States. The ICD-9-CM system is also hampered by a lack of available places left for expansion within the diagnostic categories as future updates are made. ICD-10-CM has been required for reporting mortality statistics in the United States since 1999.


What is ICD-10?

ICD-10 stands for the World Health Organization’s (WHO) International Classification of Diseases, 10th edition. It is a diagnostic coding system implemented in 1993. Naturally, it is meant to replace ICD-9, which was developed by WHO in the 1970s.  Except the United States, ICD-10 is in use almost in every country in the world.

The new ICD-10 code sets incorporate much greater specificity and clinical information and are more consistent with today’s practice. In the United States, “ICD-10”, it usually refers to the U.S. clinical modification of ICD-10: ICD-10-CM. This code set is scheduled to replace ICD-9-CM.

ICD-10-PCS (procedural coding system) will also be adopted in the United States. ICD-10-PCS will replace Volume 3 of ICD-9-CM as the inpatient procedural coding system. Current plans would see CPT remain as the coding system for physician services.

More information on WHO’s ICD-10 code set can be found at:


What is ICD-10-CM?

ICD-10-CM is the diagnosis code revision to ICD-9-CM.  There is another set of codes known as ICD-10-PCS (Procedure Coding System).


What is ICD-10-PCS?

ICD-10-PCS (Procedure Coding System) is currently designated to replace Volume 3 of ICD-9-CM for hospital inpatient use. CMS has made it very clear that its only intention is to identify inpatient facility services in a way not directly related to physician work, but directed towards allocation of hospital services and there is no intention for ICD-10-PCS to in any way, shape or form to replace CPT for the identification of physician’s work.

Regardless of whether the physician services were provided in the inpatient or outpatient setting, CPT remains the procedure coding standard for physicians. Any third party payer asking for Volume 3 procedure codes to be submitted along with CPT codes for outpatient services is in violation of HIPAA regulations and subject to fines by CMS.

ICD-10-PCS, the new procedure coding system is problematic to learn for both experienced and inexperienced coders as indicated by some preliminary inpatient hospital testing.


How is ICD-10-CM different from ICD-9-CM?

When you look in broader sense, ICD-10-CM is not much different from ICD-9-CM.  The guidelines, conventions, and rules are very similar.  The organization of the codes is very similar.  Transition to coding ICD-10-CM from ICD-9-CM by a qualified coder should not be difficult.

The actual coding process remains the same and there are some similarities, such as a valid code always contains at least 3 characters and a decimal is used after the third character.

Many improvements have been made to coding in ICD-10-CM.  For example, a single code can be found to report a disease and its current manifestation (i.e., type II diabetes with diabetic retinopathy).  In fracture care, the code differentiates an encounter for an initial fracture; follow-up of fracture healing normally; follow-up with fracture in malunion or nonunion; or follow-up for late effects of a fracture.  Likewise, the trimester is designated in obstetrical codes.

Huge increase in the number of codes under ICD-10-CM is due to laterality.  While an ICD-9-CM code may identify a condition of, for example, the ovary, the parallel ICD-10-CM code identifies four codes: unspecified ovary, right ovary, left ovary, or bilateral condition of the ovaries.

Volume of codes:

  • ICD-9-CM  13,600 (approx)
  • ICD-10-CM  69,000 (approx)

Composition of codes:

  • ICD-9-CM:
  • Mostly numeric, with E and V codes alphanumeric. Valid codes of three, four, or five digits (up to 5 characters).
  • No place holders.
  • First character is alpha (V, E) or numeric.


  • All codes are alphanumeric, beginning with a letter and with a mix of numbers and letters thereafter.  Valid codes may have three, four, five, six, or seven digits (up to 7 characters, with required 7th place character extension).
  • Place holder ‘x’ used to fill empty 4th, 5th, or 6th character positions.
  • First character is alpha; using all but the letter “U”; subsequent characters (2-5) are numeric subsequent characters (2-7) are alpha or numeric.

Duplication of code sets:

  • ICD-9-CM: Only ICD-9-CM codes are required in the current process.  No mapping is  necessary. ICD-10-CM: During transition period for a period of up to two years, systems will need to access both ICD-9-CM codes and ICD-10-CM codes.  Mapping will be necessary so that equivalent codes can be found for issues of disease tracking, medical necessity edits and outcomes studies.
  • The ICD-10-CM codes are very different from ICD-9-CM. What physician documents in the medical record remains more or less the same; However, it is how the information is "translated" into ICD coding will change. ICD-10-CM codes will be able to provide more in depth information about the patient's condition that can be more easily captured in an electronic medical record. HCFA 1500 and UB-04 billing forms are updated to accommodate the changes.

Just as with ICD-9-CM, clear physician documentation will be important in aid in assigning appropriate ICD-10-CM codes.


What is the meaning of the alpha character in ICD-10?

In the ICD-10 code set, the alpha character has a different meaning depending on where it is placed within the code. The first alpha character in every ICD-10-CM code identifies in what chapter it is placed. For example, "A" and "B" (A00-B99) are for the "Certain Infectious Diseases" chapters and "C" and half of the "D" chapters (C00-D49) for "Neoplasms".

In the middle of the ICD-10-CM are alpha characters, which do not have a specific meaning. They are just for expanding the code set to allow for more codes.

Alpha character placed at the end of a code usually means "episode of care". For example, A = initial encounter, B = subsequent encounter, S = sequela. Another alpha character explanation at the end of the code will identify different types of fractures and/or the episode of care of a fracture.

ICD-10-PCS is different. Each of the characters in the ICD-10-PCS system has a specific meaning. If you go through the code set, you will find that under every character (1-7), each character will mean something different depending on the placement of the character.


Where can I learn more about ICD-10-CM and ICD-10-PCS?

Detailed discussion of the features and challenges of ICD-10-CM and ICD-10-PCS are available from:


Why the United States is implementing ICD-10-CM?

ICD-9-CM has several problems. Foremost, it is out of room. Because the classification is organized scientifically, each three-digit category can have only 10 subcategories. Most numbers in most categories have been assigned diagnoses. Medical science keeps making new discoveries, and there are no numbers to assign these diagnoses.

More detailed codes of ICD-10-CM combined with computer science will allow better analysis of disease patterns and outcome of treatment that can advance medical care. These details will streamline submission of claims and these details will make the initial claim easily understandable for payers.

Adoption of ICD-10 will reduce payment errors and speed reimbursement throughout the industry while improving data sharing opportunities across global and industrial boundaries. If used strategically, ICD-10 can enhance quality measurement and research to inform changes in healthcare.

Further, ICD-10-CM coding system provides a significantly increased amount of options for coding medical diagnoses that reflect modern medical knowledge and terminology. The increased availability of codes allows for much greater precision and specificity within the choice of diagnosis codes. ICD-10-CM also has built-in flexibility for future expansion to add new codes for medical diagnosis.

The fact is that, ICD-9-CM is running out of codes. Hundreds of new diagnosis codes are submitted by medical societies, quality monitoring organizations and others annually. ICD-10-CM will allow not only for more codes but also for greater specificity and thus better epidemiological tracking. This will allow providers to better identify certain patients with specific conditions that will benefit from tailored disease management programs, e.g. diabetes, hypertension, and asthma.


How many diagnosis codes are there in ICD-10-CM compared to ICD-9-CM?

  • ICD-9-CM 13,600 (approx)
  • ICD-10-CM 69,000 (approx)


How can I prepare for ICD-10-CM? Is it too early to learn ICD-10?

For doing coding with ICD-10-CM, the coder requires a more advanced knowledge of anatomy and physiology. More detailed documentation and an understanding of what must be included in the medical record documentation is required. Then only we will be able to assign the correct diagnosis code.

There is no need to hurry and panic though there will be a need for significant education and training for physicians, coders and other health care personnel to fully implement this major code change. We at CodersClub believe it is too early to go for any kind of training immediately. If one gets trained today, it will be too difficult to remember when actual implementation begins.

However, In order to avoid rejections and disturbance in the revenue cycle, staff of medical facilities must get trained thoroughly and complete end-to-end testing prior to the compliance date. This end-to-end testing is essential to ensure interoperability of processes and systems. Hence, advance planning is essential.


What are the implementation dates for ICD-10-CM and ICD-10-PCS?

Health plans, health care clearinghouses, and certain health care providers - all covered entities that bill Medicare for services must begin using the ICD-10 code sets on Oct. 1, 2013.

Below are the two regulations:

* The Centers for Medicare and Medicaid Services (CMS) announced in January that ICD-10-CM will be implemented into the HIPAA mandated code set on Oct. 1, 2013. * On January 16, 2009, the Department of Health and Human Services released the HIPAA Administrative Simplification: Modifications to Medical Data Code Set Standards to Adopt ICD-10-CM and ICD-10-PCS Final Rule (CMS-0013-F). The compliance date for implementation of the ICD-10-CM/PCS Coding System is October 1, 2013 for all covered entities.


What is GEM?

General Equivalence Mappings (GEM) were developed by CMS and CDC, with collaboration of the AHIMA and the AHA, as a tool to assist with the conversion from ICD-9-CM codes to ICD-10-CM and the conversion of ICD-10-CM codes back to ICD-9-CM. The GEMs are forward and backward mappings between the ICD-9-CM and ICD-10-CM coding systems and are also referred to as crosswalks since they provide important information linking codes of one system with codes in the other system.
In some instances, there is not a translation between an ICD-9-CM code and an ICD-10-CM code. When there is no plausible translation from a code in one system to a code in the other system, a "No Map" flag indicator is noted.


How expensive is migration from ICD-9 to ICD-10?

There have been many questions as to the cost of implementing ICD-10. The RAND Science and Technology Policy Institute is publishing its findings on the cost and benefits of implementing ICD-10. According to the draft executive summary, providers will incur costs for computer reprogramming, the training of coders, physicians, and code users, and for the initial and long-term loss of productivity among coders and physicians. The cost of sequential conversion (10-CM then 10-PCS) is estimated to run $425M to $1.15B in one-time costs plus somewhere between $5 and $40 million a year in lost productivity.

RAND assumes the benefits as largely coming from the additional detail that ICD-10-CM and ICD-10-PCS would offer. The benefit of more accurate payments to hospitals for new procedures ranges from $100M to $1.2B. Benefits from fewer rejected claims would be $200M to $2.5B and $100M to $1B for fewer exaggerated claims. The identification of more cost-effective services and direction of care to specific populations would result in a benefit of $100M to $1.5B. This is in addition to any benefits that would come from better total disease management and better directed preventive care.

Blue Cross and Blue Shield sponsored a study to determine costs to the health care industry in adopting ICD-10-CM and ICD-10-PCS. The study indicated a cost range of $5.5-13.5 billion for systems implementation, training, loss of productivity, re-work, and contract re-negotiations during a 2-3 year implementation period. Over half of the costs would be borne by health care providers. Long term recurring costs for loss of productivity were estimated at $150 million to $380 million.


When will ICD-10 be implemented?

All HIPAA Covered Entities must begin using the new ICD-10 code sets on October 1, 2013. Healthcare organizations also must comply with the HHS regulation requiring an industry-wide upgrade to the EDI Version 5010 by January 1, 2012. Version 5010 is a pre-requisite for ICD-10.


Who will be impacted by ICD-10?

There is a greater impact on more individuals as the uses of coded data have changed so much since the adoption of ICD-9-CM over 23 years ago. Obviously, coders and physicians will require training, but there are other individuals who will be affected and thus, will need some training depending on their involvement.

Coding professionals: While ICD-10-CM has many differences from ICD-9-CM, the new classification system does retain the traditional format and many of the same characteristics and conventions and thus, should not be too difficult for experienced coders to achieve coding proficiency. An additional problem that could be encountered is a shortage of credentialed, professional coders. Currently, there is a shortage of coders skilled in both ICD-9-CM and CPT coding, and some coders may opt to retire before learning an entirely new system thus exacerbating the problem. Labor statistics predict a shortage of trained coders in the next several years.

Physicians: Physician documentation has been an obstacle to complete and accurate coding for quite some time. With the increased specificity in ICD-10-CM, this issue will continue to be an essential element to collection of good statistical data as well as the key to appropriate reimbursement.

Other healthcare professionals: Again, because of the many uses of coded data, there are multiple categories of users of coded data. These users will require varying levels of training depending on their involvement with coded data. Some of these users include:

* Non-physician clinicians/ancillary department personnel
* Quality management personnel
* Utilization management personnel
* Data quality/data security personnel
* Researchers/data analysts/epidemiologists
* Software vendors
* Information systems personnel
* Billing/accounting personnel
* Compliance officers
* Auditors
* Fraud investigators
* Government agency personnel


Where can I get an electronic copy of the ICD-10?

An electronic version of ICD-10 is currently available here:


How do I get started?

The first step in preparing your organization for ICD-10 is to conduct a comprehensive Risk Readiness Assessment followed by an Impact Analysis. CodersClub can guide you through the steps of planning and implementing ICD-10 across your organization. CodersClub is having all the capabilities to address the strategic needs of provider organizations.


Will ICD-10 code sets change before the implementation date?

ICD-10-PCS has been updated on an annual basis since 1999 and hence future updates can be expected. We strongly advise all reimbursement professionals to browse the CMS Web site on regular basis for any new versions of the guidelines, index, and tabular list before implementation. ICD-10-CM and PCS index and tabular list are available at the CMS Web site:


What information systems will be affected by the change to ICD-10?

As per AHIMA’s recent publication many of the systems will be affected by the change. These systems are used at physician practices, hospitals, payers and clearinghouses:

  • Accounting systems.
  • Aggregate data reporting.
  • Billing systems.
  • Case management.
  • Case-mix systems.
  • Clearinghouse EDI systems.
  • Clinical protocols.
  • Clinical reminder systems.
  • Clinical systems.
  • Decision-support systems.
  • Disease management systems.
  • Encoding software.
  • Medical necessity software.
  • Medical record abstracting.
  • Payer claims adjudication systems.
  • Performance-measurement systems.
  • Physician practice management systems.
  • Provider profiling systems.
  • Quality management.
  • Registration and scheduling systems.
  • Test-ordering systems.
  • Utilization management.


end faq

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ICD-10 Corner

9 benefits of ICD-10

1. Measuring the quality, safety and efficacy of care
2. Designing payment systems and processing claims for reimbursement
3. Conducting research, epidemiological studies, and clinical trials
4. Setting health policy
5. Operational and strategic planning and designing healthcare delivery systems
6. Monitoring resource utilization
7. Improving clinical, financial, and administrative performance
8. Preventing and detecting healthcare fraud and abuse
9. Tracking public concerns and assessing risks of adverse public health events

More details..

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