Note similarities, differences between ICD-9-CM and ICD-10-CM
With so much attention focused on how ICD-10-CM is different from ICD-9-CM, coders could easily overlook the similarities between the two systems. With a little over a year to go before the transition, now is a good time to review how the systems are the same and highlight some of the most significant differences.
The most obvious difference is the length and structure of the codes. In ICD-9-CM, codes are three to five digits in length. In ICD-10-CM, codes can be between three and seven characters long. ICD-10-CM includes both alphabetic and numeric characters and all codes begin with a letter.
On the similarity side, 90-95% of the guidelines are staying the same, says Shannon E. McCall, RHIA, CCS, CCS-P, CPC, CPC-I, CEMC, CCDS, director of coding and HIM at HCPro.
For example, ICD?10?CM guidelines continue to state that signs and symptoms that are associated routinely with a disease process should not be assigned as additional codes, unless otherwise instructed by the classification, says Katherine Abel, CPC, CPMA, CPC?I, CMRS, director of curriculum for AAPC in Salt Lake City.
Coders will still code additional signs and symptoms that may not be associated routinely with a disease process.
Another thing that won’t change—coders still need to look in the Tabular List for the final code. “You can’t be an index coder,” McCall says. As in ICD-9-CM, codes in ICD-10-CM may have additional characters not listed in the Alphabetic Index. In addition, codes may have instructional notes, such as “use additional code” or “sequence first.”
Coders will still find “not otherwise specified” (NOS) and “not elsewhere classified” (NEC) codes in ICD-10-CM. NOS codes are used when the physician does not document enough information for coders to select a more specific code.
For example, if the physician documents “contact dermatitis” but does not specify the cause, coders report ICD-9-CM code 692.9 (contact dermatitis and other eczema, unspecified cause).
In ICD-10-CM, that code becomes L23.9 (allergic contact dermatitis, unspecified cause).
NEC codes are used when the physician provides the detail, but no code exists to report it. In ICD-9-CM, coders report 795.19 for other abnormal pap smear of the vagina and vaginal HPV. In order to use this code, the physician must document an abnormal finding that does not have its own code.
In ICD-10-CM, coders will use R87.628 to report the abnormal pap smear, NEC.
Even though ICD-10-CM codes include more detail than ICD-9-CM codes, coders will still have the option to use an unspecified code, McCall says. What remains unclear is how payers will reimburse for the unspecified codes.
Coders will also still have default codes, McCall says. In ICD-9-CM, when a physician simply documents diabetes, coders report 250.00 (diabetes mellitus without mention of complication, not stated as uncontrolled).
In ICD-10-CM, diabetes is subdivided into more categories. However, if the physician doesn’t specify the type, coders will default to Type 2.
Coders also have defaults for fractures in ICD-10-CM, McCall says. If the physician does not indicate whether the fracture is displaced or nondisplaced, select the code for displaced. In addition, if the physician does not document whether the fracture is open or closed, code it as closed.
Parentheses will still identify non-essential modifiers, McCall says. The absence or presence of terms in parentheses does not affect code selection.
In the Alphabetic Index, brackets will still designate manifestation codes. Brackets in the Tabular List will still identify synonyms or alternate terminology.
Differences between ICD-9-CM and ICD-10-CM
The two coding systems are not identical, of course, and coders will rarely find a one-to-one correlation between ICD-9-CM codes and ICD-10-CM codes. If the codes mapped one-to-one, there would be little value in moving to a new coding system.
The biggest reason coders will find multiple ICD-10-CM codes to match one ICD-9-CM code is the biggest reason for the increased number of codes in ICD-10-CM: laterality.
ICD-9-CM codes don’t specify laterality. For example, a patient suffers a contusion to the elbow. In ICD-9-CM, coders have one option: 923.11 (contusion of upper limb, elbow). In ICD-10-CM, coders have three choices:
- S50.00, contusion of unspecified elbow
- S50.01, contusion of right elbow
- S50.02, contusion of left elbow
These are not complete ICD-10-CM codes, however, because of another difference between the two systems. Some, but not all, ICD-10-CM codes require a seventh character to denote the episode of care, McCall says. For the elbow contusion, coders would add one of the following three choices:
- A, initial encounter
- D, subsequent encounter
- S, sequela
Coders will use these three seventh characters the most for everything from abrasions to contusions to sprains and strains.
Be sure to check which list of seventh character extensions apply to each particular set of codes. Fracture codes have longer lists of possible seventh characters to account for how well the fracture is healing.
For a wrist fracture, coders can only report one of these seventh characters:
- A, initial encounter for closed fracture
- B, initial encounter for open fracture
- D, subsequent encounter for fracture with routine healing
- G, subsequent encounter for fracture with delayed healing
- K, subsequent encounter for fracture with nonunion
- P, subsequent encounter for fracture with malunion
- S, sequela
Other fractures have an even longer list of possible seventh characters:
- A, initial encounter for closed fracture
- B, initial encounter for open fracture type I or II
- C, initial encounter for open fracture type IIIA, IIIB, or IIIC
- D, subsequent encounter for closed fracture with routine healing
- E, subsequent encounter for open fracture type I or II with routine healing
- F, subsequent encounter for open fracture type IIIA, IIIB, or IIIC with routine healing
- G, subsequent encounter for closed fracture with delayed healing
- H, subsequent encounter for open fracture type I or II with delayed healing
- J, subsequent encounter for open fracture type IIIA, IIIB, or IIIC with delayed healing
- K, subsequent encounter for closed fracture with nonunion
- M, subsequent encounter for open fracture type I or II with nonunion
- N, subsequent encounter for open fracture type IIIA, IIIB, or IIIC with nonunion
- P, subsequent encounter for closed fracture with malunion
- Q, subsequent encounter for open fracture type I or II with malunion
- R, subsequent encounter for open fracture type IIIA, IIIB, or IIIC with malunion
- S, sequela
ICD-10-CM uses the Gustilo-Anderson system to identify the severity of the soft tissue damage for open fractures. Only three categories of codes in ICD-10-CM require the Gustilo-Anderson classifications:
- S52, fracture of forearm
- S72, fracture of femur
- S82, fracture of lower leg, including ankle
If the physician documents an open fracture, but does not specify the amount of soft tissue damage, coders should default to type I open fracture, McCall says.
One thing to note about the seventh character extension: it must go in the seventh position in the code. The elbow contusion codes only have five characters, so coders must add a placeholder (X) to the code. For an initial encounter for a left elbow contusion, coders would report S50.02XA.
Coders may need to add as many as three placeholders in order to report an accurate code. Consider these examples:
- S06.0X0A, concussion without loss of consciousness, initial encounter
- O64.1XX1, obstructed labor due to breech presentation, fetus 1
- W92.XXXD, exposure to excessive heat of man-made origin, subsequent encounter
Without the placeholder(s), the code is incomplete and will result is a rejection by the payer, McCall says.
Not all of the changes in ICD-10-CM make coding more complicated. In ICD-10-CM, coders will have a much easier time with Excludes notes.
ICD-9-CM Excludes notes can mean two different things:
- A particular code is not for use with a particular condition
- A particular condition is not included in a particular code
Coders have to determine the exact meaning of the Excludes notes.
ICD-10-CM features two different Excludes notes, McCall says.
An Excludes1 note is a pure Excludes note, meaning it indicates that a coder should never use the code excluded at the same time as the code above the Excludes1 note. The two conditions cannot occur together.
An Excludes2 note means the condition is not included in the code. An Excludes2 note indicates that the condition excluded is not part of the condition represented by the code, but a patient may have both conditions at the same time. When an Excludes2 note appears under a code, coders may report both the code and the excluded code together when appropriate.
External causes codes
In ICD-9-CM, coders are used to V codes and E codes. Coders use V codes for supplementary classification of factors influencing health status and contact with health services. E codes describe the accident, circumstance, event, or specific agent that caused a patient’s injury.
ICD-10-CM still includes codes covered by the V and E codes, but the codes no longer start with those letters.
The current V codes will become Z codes in ICD-10-CM and will live in Chapter 21 (Factors influencing health status and contact with health services).
Coders will find the E codes in either chapter 19 (Injury, poisoning, and certain other consequences of external causes) or 20 (External causes of morbidity and mortality). In ICD-10-CM, the codes will fall within the S00-Y99.9 codes.
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