What is a Diagnosis Code? - Definition & Uses

Instructor: Rachel Torrens

Rachel is a Nurse Practitioner with experience working as a high school teacher, skin surgery center, and as a family NP.

When you think of lifesaving medical care, groundbreaking scientific research and critical legislation writing, you don't think about the one subject that links them all: medical coding. In this lesson, learn the vital importance of diagnosis codes.

The Importance of Coding

At some point, we have all gotten a glimpse of a medically based television show. You know the ones where you see incredibly good-looking men and women in scrubs running down a hospital's hallway. While this makes for gripping television, it completely omits a critical part of a healthcare provider's job.

Paperwork. It's a less stimulating but equally important part of a provider's job. Everyone in the medical community, from nurse's aide to cardiac surgeon, must deal with documentation. This is true in the United States and hundreds of other countries.

As you might imagine, there's a lot of information that needs to be recorded by millions of medical professionals all over the world. In an effort to streamline and unify information, the World Health Organization (WHO) created the International Classification of Diseases (ICD) coding system. This coding system has been in place for over 60 years and is updated at regular intervals. The first ICD released by the WHO in 1948 was the ICD-6. In 2015, they released the ICD-10, which is currently in use today. But what exactly is the ICD?

It's All in the Code

The ICD is comprised of thousands and thousands of diagnosis codes. A diagnosis code is a combination of letters and/or numbers assigned to a particular diagnosis, symptom or procedure.

For example, let's say Cheryl comes into the doctor's office complaining of pain when urinating. The healthcare provider performs a urinalysis and discovers several abnormal findings that indicate an infection. The provider concludes she has a urinary tract infection (UTI). On the check-out slip, the provider will reference several codes:

  1. N39.0 - which stands for a urinary tract infection
  2. R82.90 - which stands for unspecified abnormal findings in urine.

As you can probably guess for the above examples, these codes can get very specific. Since there are thousands of diagnoses that can be given depending on the patient's problem, there are thousands of codes in the ICD manual. The current ICD manual is over one thousand pages long and weighs almost eight pounds.

Furthermore, there are codes for when no diagnosis is found, such as Z00.129, which represents a well child examination. There are codes for when a diagnosis cannot be made but a symptom is identified, such as R06.02, which represents shortness of breath. There are also codes for when a procedure is performed, such as Z01.10, which represents a hearing test with normal results.

Uses of the ICD Code

So, who uses this incredibly complicated coding system? Well, that's part of the beauty of the system. This ICD coding, while complex, allows for global unification of medical data. It also allows for streamlining of information that hundreds of people may need to access.

Let's return to Cheryl and her urinary tract infection. On her check-out sheet, the provider wrote the diagnosis code from the ICD to define Cheryl's problem. This sheet will then go to the billing department, and a coder will enter it into the office's system to get reimbursement from the insurance company.

Also, Cheryl's diagnosis code will go into a medical database. From this database, a researcher can find that over 8 million people per year are diagnosed with UTIs, making it is a worthy topic to study. Likewise, a health information technologist will realize urinary tract infections are a common ailment and terminology related to them needs to be available in electronic medical record technology. Finally, policy makers will include code N39.0 for urinary tract infections in legislation detailing federal coverage of such conditions. Whoa. That's some journey for one tiny diagnosis code, but this is the impact it can have!

Using ICD coding information, the WHO can generate maps showing where certain illnesses are prevalent.
world map of illness occurrence

So, to recap, all of these groups utilize the ICD coding system for various purposes:

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