Using the ICD-10-CM

Selecting a Code

To select an ICD-10-CM code, follow these steps:

Step 1: Look up the term in the Alphabetic Index, an alphabetical list of terms and their corresponding code or category

Step 2: Verify the code in the Tabular List, a structured list of codes divided into chapters based on body system or condition

Alphabetic Index

The Alphabetic Index helps you decide which section to refer to in the Tabular List. It doesn’t always give the full code. The Alphabetic Index has 4 parts:

1. Index to Diseases and Injuries
2. External Causes of Injury Index
3. Table of Neoplasms
4. Table of Drugs and Chemicals

Table of Neoplasms

To properly code a neoplasm, you must analyze documentation in the medical record to decide if it says the neoplasm:

• Is malignant, primary
• Is malignant, secondary
• Is malignant, Carcinoma CA in situ (confined or noninvasive)
• Is benign
• Has uncertain behavior
• Has an unspecified behavior

Table of Drugs & Chemicals

The Table of Drugs and Chemicals lists combination codes that include the substance taken, as well as the intent. It also lists industrial solvents, corrosive gases, noxious plants, pesticides, and other toxic agents. Use this table to look up poisonings and external causes of adverse effects.

Main Terms & Subterms

The Alphabetic Index sequences main terms alphabetically. Main terms are key words often associated with documentation in medical records. Always search for a code in the Alphabetic Index by main terms, which are based on:

• Diagnosis
• Symptom
• Condition

Tabular List

The Tabular List presents codes in number order. Since all ICD-10-CM codes start with a letter, all code categories are in alphanumeric order, according to the first characters. This chart supplies the Tabular List chapters, category ranges, and corresponding body systems or conditions.

Tabular List Chapters

Chapter	Categories	Description
1	A00-B99	Certain infectious and parasitic diseases
2	C00-D49	Neoplasms
3	D50-D89	Diseases of the blood and blood-forming organs and certain disorders involving the immune mechanism
4	E00-E89	Endocrine, nutritional and metabolic diseases
5	F01-F99	Mental, Behavioral and Neurodevelopmental disorders
6	G00-G99	Diseases of the nervous system
7	H00-H59	Diseases of the eye and adnexa
8	H60-H95	Diseases of the ear and mastoid process
9	I00-I99	Diseases of the circulatory system
10	J00-J99	Diseases of the respiratory system
11	K00-K95	Diseases of the digestive system
12	L00-L99	Diseases of the skin and subcutaneous tissue
13	M00-M99	Diseases of the musculoskeletal system and connective tissue
14	N00-N99	Diseases of the genitourinary system
15	O00-O9A	Pregnancy, childbirth and the puerperium
16	P00-P96	Certain conditions originating in the perinatal period
17	Q00-Q99	Congenital malformations, deformations and chromosomal abnormalities
18	R00-R99	Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified
19	S00-T88	Injury, poisoning and certain other consequences of external causes
20	V00-Y99	External causes of morbidity
21	Z00-Z99	Factors influencing health status and contact with health services
22	U00-U85	Codes for special purposes

ICD-10-CM Coding Conventions

The conventions for ICD-10-CM are general rules of the classification independent of the guidelines. ICD-10 incorporates these conventions within the Alphabetic Index and Tabular List of ICD-10-CM as instructional notes.

7th Character

Certain ICD-10-CM categories have applicable 7th characters. You must use the applicable 7th character for all ICD-10-CM codes within the category or as notes in the Tabular List instruct. The 7th character must always be the 7th character in the data field. When it applies, codes missing this character are invalid.

Examples:

1. S13.180 (6 characters)

• Needs 7th character to be valid → S13.180A
• No placeholder needed
• Adding the 7th character only makes a valid code

2. T75.4 (4 characters)

• Needs 7th character to be valid → T75.4XXA
• 2 placeholders needed plus the 7th character to make a valid code

7th Character Encounter Coding

7th Character	Encounter Description	Examples
A	Initial Encounter: Starts at first treatment (visit) and continues for as long as the patient is getting active treatment for the condition.	Surgical treatment, emergency department encounter, and evaluation and continuing treatment by the same or a different physician.
D	Subsequent Encounter: After the patient has completed active treatment of the condition and is getting routine care for the condition during the healing or recovery phase.	Cast change or removal, an x-ray to check healing status of fracture, removal of external or internal fixation device, medication adjustment, other aftercare and follow up visits following treatment of the injury or condition.
S	Sequela: Complications or conditions that arise as a direct result of the condition.	Scar formation after a burn.

Note: For aftercare of injury, assign an acute injury code with 7th character D for the subsequent encounter.

7th Character Fracture Coding

7th Character	Description
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

Character X Used as a Placeholder in Certain Codes

ICD-10-CM uses a character X as a placeholder in certain codes to:

• Allow for future expansion
• Fill in other empty characters when a code less than 6 characters in length needs a 7th character

Default Codes

A code listed next to a main term in the ICD-10-CM Alphabetic Index is a default code, which:

• Is the condition most commonly associated with the main term
• Shows that it’s the unspecified code for the condition

Assign a default code if a condition is documented in a medical record without any additional information, like acute or chronic.

Abbreviations

Alphabetic Index abbreviations

• NEC (Not Elsewhere Classifiable) - This represents “other specified.” When a specific code isn’t available for a condition, the Alphabetic Index directs you to the other specified code in the Tabular List.
• NOS (Not Otherwise Specified) - This is the equivalent of unspecified.

Tabular List abbreviations

• NEC (Not Elsewhere Classifiable) - This represents “other specified.” When a specific code isn’t available for a condition, the Tabular List includes an NEC entry under a code to show the code as the other specified code.
• NOS (Not Otherwise Specified) - This is the equivalent of unspecified.

Punctuation

The official guidelines include these 3 punctuation symbols:

1. ( ) Parentheses

These are used in both the Alphabetic Index and the Tabular List to enclose supplementary words that may be present or absent in the statement of a disease or procedure. The terms within parentheses are referred to as nonessential modifiers.

2. [ ] Brackets

These are used in the Tabular List to enclose synonyms, alternative wording, or explanatory phrases. They’re used in the Alphabetic Index to show manifestation codes.

3. : Colons

These are used in the Tabular List after an incomplete term that requires 1 or more of the modifiers following the colon to make it assignable to a given category.

Other ICD-10-CM Coding Conventions

And

Interpret to mean “and” or ”or” when used in a code title.

Includes Notes

This appears immediately under a 3-character code title to further define, clarify, or give examples of the content of a code category.

Inclusion Terms

This is a list of terms included under certain codes to show conditions that might apply to the code.

See/See Also

• The see instruction following a main term in the Alphabetic Index shows you should reference another term. Go to the main term referenced with the “see” note to locate the correct code.
• A see also instruction following a main term in the Alphabetic Index indicates another main term may also be referenced that includes more information.

Syndromes

• Follow Alphabetic Index guidance when coding syndromes
• In the absence of Alphabetic Index guidance, assign codes for the documented manifestations of the syndrome

ICD-10-CM Features

Laterality

Several ICD-10-CM codes show laterality, specifying whether the condition occurs on the left or right side of the body or an organ or gland or is bilateral.

Obstetric codes that show trimester instead of episode of care

Report the current trimester of pregnancy, although the condition can occur in more than 1 trimester. The trimester is described in the final character of the code.

Combination codes for certain conditions and common associated symptoms and manifestations

A combination code is a single code used to classify:

• Two diagnoses
• A diagnosis with an associated secondary process or manifestation
• A diagnosis with an associated complication

Combination codes for poisonings and their associated external cause

ICD-10-CM includes combination codes for poisonings and their associated external cause. These codes name both the substance that was taken and the intent.

Instructional Notes in the Tabular List

Includes

The word “Includes” appears immediately under a 3-character code title to further define or give examples of the content of the category.

Excludes Notes

ICD-10-CM has 2 types of Excludes Notes:

• Excludes1
• Excludes2

Each note has a different definition for use, but they both show that codes excluded from each other are independent of each other.

1. Excludes1

A type 1 Excludes note is a pure excludes note. It means “NOT CODED HERE!” An Excludes1 note shows that you should never use the excluded code at the same time as the code above the Excludes1 note. An Excludes1 note is used when 2 conditions can’t occur together, like a congenital form versus an acquired form of the same condition.

2. Excludes2

A type 2 Excludes note means “Not included here.” An Excludes2 note shows that the condition excluded isn’t 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, it’s acceptable to use both the code and the excluded code together.

Etiology/Manifestation Convention

Some conditions have both an underlying etiology and multiple body system manifestations due to the underlying etiology. For these conditions, the ICD-10-CM has a coding convention that requires sequencing the underlying condition first, followed by the manifestation. Wherever this combination exists, there’s a use additional code note at the etiology code and a code first note at the manifestation code. These instructional notes show the proper sequencing order of the codes, etiology followed by manifestation.

Code Also

A code also note means you may need 2 codes to fully describe a condition. But this note doesn’t provide sequencing direction. The sequencing depends on the circumstances of the encounter.

Coding Example 1

Diagnosis: Iron deficiency anemia

Step 1: Look up the term for the diagnosis in the Alphabetic Index.

Anemia (essential) (general) (hemoglobin deficiency) (infantile) (primary) (profound) D64.9

- with (due to) (in)

- - disorder of

- - iron D50.9

- - - secondary to blood loss (chronic) D50.0

- - nutritional D53.9

- - - with

- - - - poor iron absorption D50.8

- - - - specified deficiency NEC D53.8

The Alphabetic Index lists D50.9 as the code for iron deficiency anemia.

Step 2: Verify the code D50.9 in the Tabular List.

D50.9 Iron deficiency anemia, unspecified

The Tabular List shows D50.9 as the code for Iron deficiency anemia, unspecified.

Code Assignment for this Diagnosis: D50.9

Coding Example 2

Diagnosis: Type I Diabetes Mellitus with Diabetic Nephropathy

Step 1: Look up the term for the diagnosis in the Alphabetic Index.

Diabetes, diabetic (mellitus) (sugar) E11.9

- type 1 E10.9

- - with

- - - nephropathy E10.21

The term includes a subterm indicating Type 1 diabetes with specific codes for diabetes-related conditions. The Alphabetic Index lists the code for Type 1 diabetes mellitus with diabetic nephropathy as E10.21.

Step 2: Verify the code E10.21 in the Tabular List.

E10 Type 1 diabetes mellitus

E10.2 

Type 1 diabetes mellitus with kidney complications

E10.21 

Type 1 diabetes mellitus with diabetic nephropathy
Type 1 diabetes mellitus with intercapillary glomerulosclerosis
Type 1 diabetes mellitus with intracapillary glomerulonephrosis
Type 1 diabetes mellitus with Kimmelstiel-Wilson disease

The Tabular List shows E10.21 for Type 1 diabetes mellitus with diabetic nephropathy.

Code Assignment for this Diagnosis: E10.21

Coding Example 3

Diagnosis: Acute cystitis with hematuria

Step 1: Look up the term for the diagnosis in the Alphabetic Index.

Cystitis (exudative) (hemorrhagic) (septic) (suppurative) N30.90

- acute N30.00

- - with hematuria N30.01

The Alphabetic Index shows N30.01 as the code for acute cystitis with hematuria.

Step 2: Verify the code N30.01 in the Tabular List.

N30 Cystitis

Use additional code to identify infectious agent (B95-B97)

N30.0  

Acute cystitis
N30.00 Acute cystitis without hematuria
N30.01 Acute cystitis with hematuria

The Tabular list shows N30.01 for acute cystitis with hematuria.

Code Assignment for this Diagnosis: N30.01

Coding Example 4

Diagnosis: Pneumonia

Step 1: Look up the term for this diagnosis in the Alphabetic Index.

Pneumonia (acute) (double) (migratory) (purulent) (septic) (unresolved) J18.9

Step 2: Verify the code J18.9 in the Tabular List.

J18 Pneumonia, unspecified organism

Code first, if applicable, associated influenza (J09.X1, J10.0-, J11.0-)

J18.9 Pneumonia, unspecified organism

The Tabular List shows J18.9 as the code for pneumonia, unspecified organism.

Code Assignment for this Diagnosis: J18.9

Coding Example 5

Diagnosis: Fracture of left wrist, initial encounter

Step 1: Look up the term for the diagnosis in the Alphabetic Index.

Fracture, traumatic (abduction) (adduction) (separation) – see also Fracture, pathological T14.8

- wrist, S62.10-

- - carpal – see Fracture, carpal bone

The Alphabetic Index shows S62.10- as the code for a wrist fracture. The code features a dash (-), which shows that additional characters are needed.

Step 2: Verify the code S62.10- in the Tabular List.

S62 Fracture at wrist and hand level

Note:

A fracture not indicated as displaced or nondisplaced should be coded to displaced
A fracture not indicated as open or closed should be coded to closed

The appropriate 7th character is to be added to each code from category S62
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

Scroll down the list of codes until you locate the listing for S62.10:

S62.10 Fracture of unspecified carpal bone

Fracture of wrist NOS

S62.101 Fracture of unspecified carpal bone, right wrist
S62.102 Fracture of unspecified carpal bone, left wrist
S62.109 Fracture of unspecified carpal bone, unspecified wrist

The Tabular List shows S62.102 as the code for fracture of unspecified carpal bone, left wrist. Per the instructional note, the 7th character is A, initial encounter for closed fracture. You should select A because the fracture isn’t described as open or closed.

Coding Example 6

Now, let’s review an external cause code example. You’re encouraged to voluntarily report external cause codes in the absence of a reporting mandate.

Diagnosis: Injury sustained from falling down ice-covered steps, initial encounter

Step 1: Look up the term for the diagnosis in the External Cause of Injuries Index, which is part of the Alphabetic Index.

Fall, falling (accidental) W19

- from, off, out of

- - stairs, steps W10.9

- - - due to ice or snow W00.1

The index shows W00.1 for the code for falling from steps due to ice or snow.

Step 2: Verify the code W00.1 in the Tabular List.

W00 Fall due to ice and snow

Includes: pedestrian on foot falling (slipping) on ice and snow

The appropriate 7th character is to be added to each code from category W00

A – initial encounter
D – subsequent encounter
S – sequela

W00.1  Fall from stairs and steps due to ice and snow

The Tabular List shows W00.1 as the code for fall from stairs and steps due to ice and snow. Since W00.1 only has 4 characters and A must appear in the 7th character position to show initial encounter, this is an example of a situation when you should use character X as a placeholder. Insert X twice to create 6 characters and then add the 7th character, A, at the end of the code.