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Class # 5 "Current Procedural Terminology (CPT)"


Despite how extensive it is, the ICD is just one portion of medical coding, as it covers only diagnoses. There is an entirely separate code set for medical treatments. This code set is called Current Procedural Terminology (CPT). CPT codes refer to the wide range of all medical procedures, including every task and service performed by a medical practitioner. These codes are broken down into three categories. The majority of CPT codes exist in Category I. Category II is reserved for optional performance measurement, and Category III denotes emerging technologies.


CPT codes are broken down into categories. Unlike ICD codes, the CPT codes do not exist in detailed tabular format, and are broader in their organization.

Category I is broken down into six main sections:

Codes for Evaluation and Management: 99201-99499

Codes for Anesthesia: 00100-01999; 99100-99150

Codes for Surgery: 10021-69990

Codes for Radiology: 70010-79999

Codes for Pathology & Laboratory: 80047-89398

Codes for Medicine: 90281-99199; 99500-99607

Individual sections are then broken down further. For example:

Codes for Evaluation and Management: 99201-99499

Office/other outpatient services 99201-9215

Hospital observation services 99217-99220

Hospital inpatient services 99221-99239
Consultations 99241-99255

Emergency department services 99281-99288

Critical care services 99291-99292

Because the CPT is copyrighted and run by the American Medical Association, a comprehensive list of codes is generally not made available to the public.

Category II

CPT II codes describe clinical components usually included in evaluation and management or clinical services and are not associated with any relative value. Category II codes are reviewed by the Performance Measures Advisory Group (PMAG), an advisory body to the CPT Editorial Panel and the CPT/HCPAC Advisory Committee. The PMAG is composed of performance measurement experts representing the Agency for Healthcare Research and Quality (AHRQ), the American Medical Association (AMA), the Centers for Medicare and Medicaid Services (CMS), the Joint Commission on Accreditation of Healthcare Organizations (JCAHO), the National Committee for Quality Assurance (NCQA) and the Physician Consortium for Performance Improvement. The PMAG may seek additional expertise and/or input from other national health care organizations, as necessary, for the development of Category II codes. These may include national medical specialty societies, other national health care professional associations, accrediting bodies and federal regulatory agencies.

Category II codes make use of an alphabetical character as the 5th character in the string (i.e., 4 digits followed by the letter F). These digits are not intended to reflect the placement of the code in the regular (Category I) part of the CPT codebook. Appendix H in CPT section contains information about performance measurement exclusion of modifiers, measures, and the measures' source(s).


Currently there are 11 Category II codes. They are:

(0001F-0015F) Composite measures

(0500F-0575F) Patient management

(1000F-1220F) Patient history

(2000F-2050F) Physical examination

(3006F-3573F) Diagnostic/screening processes or results

(4000F-4306F) Therapeutic, preventive or other interventions

(5005F-5100F) Follow-up or other outcomes

(6005F-6045F) Patient safety

(7010F-7025F) Structural Measures

CPT II codes are billed in the procedure code field, just as CPT Category I codes are billed. Because CPT II codes are not associated with any relative value, they are billed with a $0.00 billable charge amount.

Category III – Emerging technology (Category III codes: 0016T-0207T)


Since medical procedures and services are often complex, we sometimes need to supply additional information when we’re coding. CPT Modifiers, like modifiers in the English language, provide additional information about the procedure. In English, a modifier may describe the who, what, how, why, or where of a situation. Similarly, a CPT modifier may describe whether multiple procedures were performed, why that procedure was necessary, where the procedure was performed on the body, how many surgeons worked on the patient, and lots of other information that may be critical to a claim’s status with the insurance payer.

CPT Modifiers are always two characters, and may be numeric or alphanumeric. Most of the CPT modifiers you’ll see are numeric, but there are a few alphanumeric Anesthesia modifiers that we’ll toward the end of this course.

CPT modifiers are added to the end of a CPT code with a hyphen. In the case of more than one modifier, you code the “functional” modifier first, and the “informational” modifier second. The distinction between the two is simple: you always want to list the modifiers that most directly affect the reimbursement process first.

There’s a straightforward reason to this, too. While CMS-1500 and UB-04 forms, the two most common claim forms, have space for four modifiers, payers don’t always look at modifiers after the first two. Because of this, you always want the most important modifiers to be visible. We’ll return to this point in a few examples after we examine the CPT modifiers.

In order to communicate this extremely detailed information in an efficient, standardized way, the AMA created CPT modifiers. CPT modifiers are two-character suffixes that healthcare providers or coders attach to a CPT code to give additional information about the procedure documented. CPT modifiers are always two characters in length. They may consist of two numbers from 21 to 99, two letters, or a mix (alphanumeric). These modifiers are appended to the initial CPT code by a hyphen.

Some examples of common CPT modifiers include:

  • -53 (discontinued procedure)

  • -59 (distinct procedural service)

  • -79 (unrelated procedure or service performed by the same physician during the postoperative procedure).

Some common letter-based modifiers include:

  • -LT (denotes a procedure on the left side of the body)

  • -RT (denotes the right side of the body),

  • -GC (identifies that a service has been performed by residents or students under the guidance of a teaching physician).

If you had to code a partial mastectomy of the left breast, you would use the CPT code 19302 for the procedure, with the modifier –LT to describe on which side of the body the procedure took place. Our code would read 19302-LT. If, however, the procedure had to be stopped because of a concern for the well-being of the patient, you would add another modifier: -53. The new code would read 19302-LT-53. Note that this is a simplified example, and that a procedure as complex as a mastectomy often has numerous additional codes).

Certain CPT modifiers are only used with a particular type of procedure or service. For instance, the modifier –LT used above is only valid when describing a procedure on an appendage or organ paired in the body, such as the lung, kidney, leg, or breast. The modifiers, -21, -24, -25, and -27 are only used for evaluation and management. Also, note that unlike CPT codes and ICD codes, CPT modifiers are not necessarily grouped into related procedures.

Functional vs. informational modifiers

There are a number of additional rules that govern the use of CPT modifiers. Coders must constantly look out for certain restrictions, formats, and guidelines, as a miscoded CPT modifier can result in a denied claim. Medical coders typically only use two CPT modifiers. While there is room for up to four modifiers on the CMS 1500 and UB-04 claim forms, the Center for Medicare and Medicaid Services (CMS) or other payers may not recognize modifiers after the first two. For this reason, coders should list first the modifiers that will affect reimbursement. These are often called functional or pricing modifiers, while modifiers that provide information about the procedure are known as informational. There are certain CPT modifiers, such as -22 (for unusual procedural services) and -52 (for reduced services), that affect reimbursement if documentation supports the use of this modifier.

Take, for example, the partial mastectomy of the left breast (code 19302-LT-53). If you were to swap out the -53 (discontinued procedure) with the functional modifier -52 (for reduced services), you would then code the whole procedure 19302-52-LT. Note that the functional modifier (-52) now comes before the informational modifier (-LT). If the informational modifier is listed first in a claim, an insurance company will deny that claim and return it to the healthcare provider.

Certain modifiers also have guidelines specific to them. The modifier -51, for multiple procedures, is one of the more commonly used CPT modifiers. In the instance of multiple procedures provided by the same specialist or healthcare provider, a coder would list the initial procedure’s CPT code, then append the modifier -51 to the end of the code for the additional procedure or procedures. Certain procedures, however, are listed in the CPT book as “-51 exempt,” and coders must be aware of this distinction.

Note that some modifiers can be used in conjunction with each other (like -23, unusual anesthesia, and -47, for anesthesia by surgeon). Others contradict one another and cannot be included in the same code For example, the modifier –LT (procedure on the left of two paired appendages or organs) cannot be coded with the modifier -50, which describes a bilateral procedure

Using the HCPCS

Not all insurance providers accept the CPT. Medicare and Medicaid (both of which will be discussed below) use the Healthcare Common Procedure Coding System (HCPCS). This coding system is comprised of two levels. Level one consists of the CPT codes and is identical in its implementation. Level two is a coding system that is used to identity medical products and services not included in CPT codes, such as ambulance services, prosthetics, and durable medical equipment. These products and services are usually used outside of the medical practitioner’s office, and Medicare/Medicaid often cover these services where other insurance providers may not.

Required Assignments:
Please view the videos below:


​Optional reading assignment:

(Understanding Health Insurance, by Green and Rowell. 10th Edition)

"Overview of CPT" pages 202-211

"CPT Index" pages 212-214

CPT 2021.jpg

Recommended CPT Book:


CPT 2021 Professional Edition is the definitive AMA authored resource to help health care professionals correctly report and bill medical procedures and services. The AMA publishes the only CPT codebook with the official CPT guidelines. The CPT 2021 Professional Edition codebook features the following enhancements:

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