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Ch. 01

ICD-10 Introduction

Safety, privacy and efficiency are at the forefront of every medical administrator’s mind. With health on the line they must take these responsibilities seriously. Encoding medical conditions and procedures allows them to ensure a high level of anonymity while transmitting data as quickly as possible. While you don’t interact with these medical coders in the same way you do doctors and nurses, they play a huge role in the health care system. Their work allows doctors to quickly review medical files to determine what might be going on with a patient. It is a large and technical profession. According to the Bureau of Labor Statistics there were 172,000 employed coders in 2008, and this number is expected to increase greatly by 2018.


In the first chapter of Patricia Aalseth’s Medical Coding the history of the profession is explained. Medical coding has its roots in Bocaccio’s studies of the Black Death in the 14th century. He documented the spread and symptoms of the plague. Even after the initial devastation, outbreaks of the disease wreaked havoc across Europe for the next few centuries. Using Boccaccio’s information, the London Bills of Mortality were published in the 1600s to help citizens avoid areas the plague was most concentrated. The study of epidemiology was born.

In 1853 the International Statistical Congress met in Brussels and recommended a universal system defining causes of death. William Farr, well known for his work studying cholera, was commissioned for the project. The protocol was adopted in 1864. After Farr’s death, Jacques Bertillon continued the project. He developed a revised version called the International List of Causes of Death, the direct precursor to the ICD. It was also the first of these systems to be adopted internationally.

This protocol underwent updates but persisted for the most part unchanged until the Fifth International Conference for the Revision of the International List of Causes of Death in 1938. During this assembly the Conference realized a system of coding diseases would be beneficial to medical facilities around the world. The protocol was published in 1944 to record disease statistics in the US and UK. 1945 brought another huge change with the merging of the two systems to form the Proposed Statistical Classification of Diseases, Injuries and Causes of Death. The following year, at the WHO hosted International Health Conference, the proposal was revised and titled the International Classification of Diseases, Injuries, and Causes of Death. The document saw further revisions and its official publication during the Sixth Revision in 1948.

The medical practice changes quickly and these codes needed frequent review to stay current. Every ten years, from 1955 onward, the system was updated. After the Ninth Revision in 1975 the WHO realized it needed more experience with the codes to determine where improvements could be made. The Tenth Revision was proposed in 1989 and released in 1994. While the United States is still gearing up for adopting the system, it has already been implemented in countries around the world. Early drafts of ICD-11 are already available online and the final product is due in 2015.

  • Check out the World Health Organization’s official history of the ICD system and its roots in the development of epidemiology. This is the most comprehensive documentation of the milestones that directly influenced the world medical coding standards. The ins and outs of revision and approval are discussed in detail.
  • The American Health Information Management Association has a brief history of ICD-10-PCS, the system used to document medical procedures. This coding protocol complements ICD-10-CM, used to record conditions. PCS stands for Procedural Coding System while CM means Clinical Modification. It includes a general outline of how this system differs from ICD-9-PCS and the advantages of these changes.


While there are many improvements in ICD-10, there are relatively few changes to the format of coding. This is not to say that medical coders don’t need to learn anything new. There are many alterations to the specificity and expansiveness of the new system. Where ICD-9-CM only had 13,000 codes ICD-10-CM boasts 68,000. The format has been lengthened and the rearranged to more accurately describe different types of injuries. For example, sensory receptor injuries are separated from nervous disorders in ICD-10. There is a lot more to know in ICD-10.

With the increased complexity comes increased accuracy in documenting conditions. While ICD-9 had no way to distinguish the side of the body exhibiting injury, this is included for every applicable instance in ICD-10. Different stages of disease, trimester indications for pregnancy and codes that combine conditions with relevant information are all recognized by improvements made in ICD-10. Medical coders will be able to more accurately document patient health, leading to more efficient health practices and less room for error. Coded documents will require less supplementary paperwork to distinguish between the ambiguities of ICD-9. Overall the changes will increase accessibility and efficacy of information in medical files. They require adaptation by doctors recording their procedures and medical information specialists accurately encoding the details. With the participation of these professionals the health care industry stands to improve efficiency and precision through the new system.

  • The Centers for Medicare & Medicaid Services are heavily involved in the revision and transition of medical billing. Their introduction to ICD-10 is well laid out and intuitive, even for nonexperts. They describe the significant differences between ICD-9 and 10 and supply comparative examples to see improvements. The end of the document includes advice on preparing for the switch and a few sites with more detailed information.
  • CMS’ ICD-10 overview is a presentation on many aspects of medical coding. It covers the history of ICD-9, the reasons the switch is necessary and the additional features of the new protocol. In addition to CMS’ Pat Brooks, it includes perspectives from representatives of the Center for Disease Control, the American Health Association and the American Health Information Management Association.
  • The ICD-10-CM Primer by AHIMA does a good job of comparing the new system with ICD-9-CM. This article only applies to the Clinical Modification codes and not those in the Procedural Coding System. It might lack some of the interesting charts and tables of other documents, but includes more specific information about the development and differences between the two.
  • The Centers for Medicare & Medicaid Services has a detailed page devoted to information on ICD-10. Much of this is included in their introduction, listed above. The most useful pages here are the GEMs, or General Equivalence Mappings, from ICD-9 to ICD-10. These give an idea of how to encode ICD-9 data in the new format. While these are not universally applicable to all conditions, they do give a good place to start for medical coders wanting to stay a step ahead.