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ICD-10 Transition tips and tools

ICD-9 vs. ICD-10: Learning the Differences

During the development of the ICD-10 Procedure Coding System (ICD-10-PCS), significant changes were made that affect the format of procedure coding and how coders will look up codes in the index and tables for code assignment. This article will present the differences.

Principles of Development
Four general principles were followed during the development of ICD-10-PCS codes.

  • The procedure description does not include diagnostic information (i.e., a specific disease or disorder, such as hernia repair, neoplasms, cleft lip or palate).
  • The options for "not otherwise specified" (NOS) have been restricted as a minimum level of specificity is required for each procedure component.
  • There is limited use of the "not elsewhere classified" (NEC) option as there is a minimum level of specificity required for each procedure code. An example of the limited NEC option involves new devices, which are continually released into the healthcare market. As a result, our coding systems cannot keep up with the constant changes. An "other device" option must be used in code assignment until the new device can be added to the coding system.
  • All procedures that are currently performed can be specified (level of specificity) within ICD-10-PCS. 

ICD-10-PCS Coding Conventions
As we have all heard by now, the ICD-10-PCS codes consist of seven characters, which include the numbers 0-9 and the alphabet, excluding the letters I and O to avoid confusion with the digits 1 and 0.  Each character represents an axis of classification that provides specific information about the procedure performed. Up to 34 possible values can be assigned to each axis of classification within the seven-character code (e.g., the fifth character, or axis of classification, identifies one of seven different types of approach). The ICD-10-PCS system is set up to easily allow for expansion for increased detail in procedural coding. This means that the valid values for an axis of classification can easily be added to as the need arises.

An alphabetic index is included in the PCS manual that will be used to help locate the appropriate table necessary to identify the correct procedure code. However, consulting the alphabetic index first is not a requirement in ICD-10-PCS code assignment. It is appropriate to proceed directly to the PCS tables for code assignment. 

All seven characters within the PCS tables must be specified in order to be a valid code. If the physician documentation is incomplete for coding purposes, a query should be initiated for clarification of the procedure documentation. However, the physician is not expected to use the same terms included in the PCS code descriptions. The coder is therefore not required to query the physician when the correlation between the physician documentation and the PCS term is clear. For example, if the physician documents "partial resection," the coder can correlate that phrase to the root operation "excision" without querying the physician.

Procedures in ICD-10-PCS are divided into sections that identify the general type of procedure being performed (e.g., medical and surgical, osteopathic, placement).  The table below shows the breakdown of the sections.


Medical and surgical








Measurement and monitoring


Extracorporeal assistance and performance


Extracorporeal therapies




Other procedures






Nuclear medicine


Radiation oncology


Physical rehabilitation and diagnostic audiology


Mental health


Substance abuse treatment

As stated above, each PCS code is made up of seven characters. The second through seventh characters mean the same thing within each section but may mean different things in the other sections. In all sections, the third character specifies the general type of procedure performed (such as resection or fluoroscopy), while the other characters give additional information regarding the body part and approach. 

In ICD-10-PCS, values 027 specify the Medical and Surgical (2) section, the Heart and Great Vessels (2) body system, and the root operation Occlusion (L) and its definition.  The lower section of the table identifies all the valid combinations of the characters four through seven. 

Section: 0 -- Medical and surgical

Body System: 2 -- Heart and great vessels

Operation: L -- Occlusion: Completely closing an orifice or the lumen of a tubular body part

Body Part




R Pulmonary artery, left

0 Open

3 Percutaneous

4 Percutaneous endoscopic

C Extraluminal device

D Intraluminal device

Z No device

T Ductus arteriosus

S Pulmonary vein, right

T Pulmonary vein, left

V Superior vena cava

0 Open

3 Percutaneous

4 Percutaneous endoscopic

C Extraluminal device

D Intraluminal device

Z No device

Z No qualifier

The above information provides the building blocks of the upcoming ICD-10 procedure coding system. The next step, to be presented in future articles, will summarize the set-up of PCS coding and the breakdown of the sections listed in the first table.

Susan M. Howe is a senior healthcare consultant with Medical Learning Inc. (MedLearn), St. Paul, MN.

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