Medical Coding Vocabulary and Key Terms

When it comes to medical coding, there is a lengthy list of key terms and vocabulary that are used by coders on a daily basis. It is important for medical coders to become very familiar with these terms, and those with a firm grasp will be able to provide an effective and expeditious job performance. Here is a look at some key terms and vocabulary that every medical coder should know.

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– This stands for the International Classification of Diseases Tenth Edition and is the system used for classifying codes of illnesses. It went into effect in 2015, replacing the ICD ninth edition.


– This stands for the Current Procedural Terminology that has been established by the American Medical Association. It describes services of the surgical, medical and diagnostic varieties.

Category Codes

– This is a three-digit code that follows a particular condition. For example, a condition such as COPD (Chronic Pulmonary Obstructive Disease) is followed by a category code of 496.

Subcategory Codes

– This is a four-digit code, which serves the purpose of describing the code in greater detail. For example, a subcategory code of HTD (Hypertension Disorder) 401.9 aims to provide a bit more detail of the hypertension disorder.

Subclassification Codes –

These are codes that require five digits because of the intricate detail involved. There are lots of subclassification codes that end with two zeros, which follow three digits and a decimal point (250.00).

Main Term –

This is the term that needs to be looked up in a medical coder’s book index. If a person has chronic bronchitis, then the coder would look up the code for bronchitis.

Default Code

– This is sometimes called an unspecified code as well. It is the code listed next to the main term and is used when there is no specific code for the condition.

Modifiers –

These are two characters and may be either numbers or letters. They are added to the end of a code with a hyphen. A modifier may indicate whether or not a service was completed whether it was a success or failure.

New and Established Pts

– This refers to new or established patients. The new distinction describes patients who have not received services from a physician or from a similar specialty physician in the previous three years. The established distinction refers to those patients who have received services in the prior three years

E and M Coding –

Evaluation and Management coding is often used by doctors to refer to a specialty.

Healthcare Common Procedure Codes (HCPCS)

-These codes are used to identify services, supplies and products that are not included in CPT coding. These codes are applied to services not provided by a physician, but could be performed by ambulance services and other entities.

Placeholder X

– When there is only six available characters for a code and a seventh needs to be added, it is done with the character of X.

Temporary Codes

– These codes are applied to different kinds of emerging technologies. Whenever that occurs, these codes conclude with the letter T.

Relative Value Unit (RVU)

– This term is used to describe formulas produced by Medicare.

American Medical Association

– This is the group entrusted with establishing and modifying any changes of the medical coding system.

Supplemental Reports –

These are reports that are requested from health insurances to explain why a service was performed or discontinued. These are often included with CPT modifiers.

Advanced Beneficiary Notice (ABN) –

This is part of Medicare and is issued when a patient agrees to undergo a service that may not be covered by Medicare. It is a form that makes patients aware of that fact.

Nonessential modifiers –

These are the subterms which come after the main term and they are written in parenthesis. These are not mandatory but serve the function of providing more clarity to the diagnosis.

V Codes –

These are the codes that are used to identify any circumstances which might influence the care of a patient. These codes are used to identify conditions that are not considered an injury or illness.

E Codes –

These codes signify the way an injury was suffered, and it also includes the location of the injury.


– This is used to describe a disease that has taken its name from an actual person. For example, ALS is commonly called Lou Gehrig’s disease.

Tabular List

– This is a list of codes which have been placed in numerical order. Coders refer to their tabular lists quite frequently.

Combination Codes

– This represents a single code that is used for classifying two diagnoses; one with a complication or one with an associated secondary manifestation.

Principle Diagnosis

– This refers to the diagnosis code that is listed first. It is used to explain the main reason for the medical visit and is used very often by coders.