Medical Billing Basics: What is ICD?

The history of the ICD

The history of medicine across the world is a long and complicated one. It is only within the last couple centuries that we have fine-tuned how we treat, diagnose and categorize illness. Disease is a shared human experience that does not abide by borders. Therefore, it became necessary to develop a standardized system of classifying all known medical conditions that could be recognized around the world. The International Classification of Diseases, or ICD, was created to fill this need.

The History of the ICD

According to Encyclopedia Britannica Online several systems of classification were attempted before arriving at the IDC. These dated back to as early as the 1600s. It wasn’t until the nineteenth century that statisticians were employed to develop a worldwide system.

In 1893, French statistician Jacques Bertillon’s Bertillon Classification of Causes of Death became the basis for the new system. In the following years, this universal standard was regularly updated, eventually changing its name to the International List of Causes of Death and finally, the ICD.

How are ICD Codes Structured?

At the time of this article, the current iteration of the system is known as ICD-10. All ICD-10 codes follow a specific format. Every code begins with a letter of the alphabet (excluding U) followed by two numbers. After this, the fourth through seventh characters can be alphanumeric and vary in length.

According to TechTarget,”the first three characters categorize the injury, and the fourth through sixth characters describe in greater detail the cause, anatomical location and severity of an injury or illness.” Codes that are seven characters utilize the last character to specify when the effect took place in the treatment. Because the ICD is constantly updated, these codes my eventually expand or change format entirely. 


Though the ICD is used worldwide, each country uses it to varying degrees. In some countries, it is only used in cases where illnesses cause death, while in others it is only used in certain medical institutions. The World Health Organization explains that the system provides an efficient way of storing and retrieving health information. Therefore, this information can be more easily shared between medical facilities and across borders.

The ICD also allows for medical data to be analyzed for statistical purposes, such as tracking the prevalence of a disease. Other data such as death counts, symptoms, and causes are more effectively recorded thanks to this system. In addition, these statistics can be used to monitor safety and quality standards as well as reimbursements. Having this data available in a comprehensive fashion enables governments and nations to better structure their healthcare systems. It is for that reason that ICD is the basis on which the world collectively expands modern medicine.

Disclaimer: The materials contained on this website are provided for informational purposes only and do not constitute legal or other professional advice on any subject matter. Advanced Medical Practice Management does not accept any responsibility for any loss which may arise from reliance on information contained on this site.