The medical record documentation should accurately reflect the patient’s condition, using terminology that includes specific diagnoses and symptoms or clearly states the reasons for the encounter. Choosing the main term that best describes the reason chiefly responsible for the service provided is the most important step in coding. If symptoms are present and documented but a definitive diagnosis has not yet been determined, code the symptoms. For outpatient cases, do not code conditions that are referred to as “rule out,” “suspected,” “probable,” or “questionable.” Diagnoses often are not established at the time of the initial encounter/visit and may require two or more visits to be established. Code only what is documented in the available outpatient records and only to the highest degree of certainty known at the time of the patient’s visit. For inpatient medical records, uncertain diagnoses may be reported if documented at the time of discharge.
The most critical rule is to begin code selection in the alphabetic index. Never turn first to the tabular list. The index provides cross-references, essential and nonessential modifiers, and other instructional notations that may not be found in the tabular list.
The alphabetic index lists conditions, which may be expressed as nouns or eponyms, with critical use of adjectives. Some conditions known by several names have multiple main entries. Reasons for encounters may be located under general terms such as admission, encounter, and examination. Other general terms such as history, status (post), or presence (of ) can be used to locate other factors influencing health.
Scan the subterm entries, as appropriate, being sure to review continued lines and additional subterms that may appear in the next column or on the next page. Shaded vertical guidelines in the index indicate the indentation level for each subterm in relation to the main terms.
• Parentheses ( ) enclose nonessential modifiers, terms that are supplementary words or explanatory information that may or may not appear in the diagnostic statement and do not affect code selection.
• Brackets [ ] enclose manifestation codes that can be used only as secondary codes to the underlying condition code immediately preceding it. If used, manifestation codes must be reported with the appropriate etiology codes.
• Default codes are listed next to the main term and represent the condition most commonly associated with the main term or the unspecified code for the main term.
• “See” cross-references, identified by italicized type and “code by” cross-references indicate that another term must be referenced to locate the correct code.
• “See also” cross-references, identified by italicized type, provide alternative terms that may be useful to look up but are not mandatory.
• “Omit code” cross-references identify instances when a code is not applicable depending on the condition being coded.
• “With” subterms are listed out of alphabetic order and identify a presumed causal relationship between the two conditions they link.
• “Due to” subterms identify a relationship between the two conditions they link.
• “NEC,” abbreviation for “not elsewhere classified,” follows some main terms or subterms and indicates that there is no specific code for the condition even though the medical documentation may be very specific.
• “NOS,” abbreviation for “not otherwise specified,” follows some main terms or subterms and is the equivalent of unspecified; NOS signifies that the information in the medical record is insufficient for assigning a more specific code.
• Following references help coders locate alphanumeric codes that are out of sequence in the tabular section.
• Check-additional-character symbols flag codes that require additional characters to make the code valid; the characters available to complete the code should be verified in the tabular section.
To prevent coding errors, always use both the alphabetic index (to identify a code) and the tabular list (to verify a code), as the index does not include the important instructional notes found in the tabular list. An added benefit of using the tabular list, which groups like things together, is that while looking at one code in the list, a coder might see a more specific one that would have been missed had the coder relied solely on the alphabetic index. Additionally, many of the codes require a fourth, fifth, sixth, or seventh character to be valid, and many of these characters can be found only in the tabular list.
The coder must follow any Includes, Excludes 1 and Excludes 2 notes, and other instructional notes, such as “Code first” and “Use additional code,” listed in the tabular list for the chapter, category, subcategory, and subclassification levels of code selection that direct the coder to use a different or additional code. Any codes in the tabular range A00.0–T88.9, Z00–Z99.8, and U00–U85 may be used to identify the diagnostic reason for the encounter. The tabular list encompasses many codes describing disease and injury classifications (e.g., infectious and parasitic diseases, neoplasms, symptoms, nervous and circulatory system etc.).
Codes that describe symptoms and signs, as opposed to definitive diagnoses, should be reported when an established diagnosis has not been made (confirmed) by the physician. Chapter 18 of the ICD-10-CM code book, “Symptoms, Signs, and Abnormal Clinical and Laboratory Findings, Not Elsewhere Classified” (codes R00–R99), contains many, but not all, codes for symptoms.
ICD-10-CM classifies encounters with health care providers for circumstances other than a disease or injury in chapter 21, “Factors Influencing Health Status and Contact with Health Services” (codes Z00–Z99). Circumstances other than a disease or injury often are recorded as chiefly responsible for the encounter.
A code is invalid if it does not include the full number of characters (greatest level of specificity) required. Codes in ICD-10-CM can contain from three to seven alphanumeric characters. A three-character code is to be used only if the category is not further subdivided into four-, five-, six-, or seven-character codes. Placeholder character X is used as part of an alphanumeric code to allow for future expansion and as a placeholder for empty characters in a code that requires a seventh character but has no fourth, fifth, or sixth character. Note that certain categories require seventh characters that apply to all codes in that category. Always check the category level for applicable seventh characters for that category.
The ICD-10-CM Official Guidelines for Coding and Reporting govern the use of certain codes. These guidelines provide both general and chapter-specific coding guidance.
Having reviewed all relevant information concerning the possible code choices, assign the code that most completely describes the condition.
Repeat steps 1 through 9 for all additional documented conditions that meet the following criteria:
• They exist at the time of the visit AND
• They require or affect patient care, treatment, or management
Sequencing is the order in which the codes are listed on the claim. List first the ICD-10-CM code for the diagnosis, condition, problem, or other reason for the encounter/visit that is shown in the medical record to be chiefly responsible for the services provided. List additional codes that describe any coexisting conditions. Follow the official coding guidelines (see the guidelines, section II, “Selection of Principal Diagnosis”; section III, “Reporting Additional Diagnoses”; and section IV, “Diagnostic Coding and Reporting Guidelines for Outpatient Services”) on proper sequencing of codes
Step 1: The reason for the encounter was the condition, anorexia.
Step 2: Consult the alphabetic index.
Step 3: Locate the main term “Anorexia.”
Step 4: Two possible subterms are available, “hysterical” and “nervosa.” Neither is documented in this instance, however, so they cannot be used in code selection.
Step 5: The code listed next to the main term is called the default code selection. Because the two subentries (essential modifiers) do not apply in this instance, the default code (R63.0) should be used.
Step 6: Turn to code R63.0 in the tabular list and read all instructional notes.
Step 7: The Excludes 1 note at code R63.0 indicates that anorexia nervosa and loss of appetite determined to be of nonorganic origin should be reported with a code from chapter 5. The diagnostic statement does not describe the condition as anorexia nervosa, however, and does not indicate that the anorexia is of a nonorganic origin. There is no further division of the category past the fourth-character subcategory. Therefore, code R63.0 is at the highest level of specificity.
Step 8: Review of official guideline I.C.18 indicates that a symptom code is appropriate when a more definitive diagnosis is not documented.
Step 9: The default code, R63.0 Anorexia, is the correct code selection. Repeat steps 1 through 9 for any concomitant diagnoses.
Step 10: Since anorexia is listed as the chief reason for the health care encounter, the first-listed, or principal, diagnosis is R63.0. Note that this is a chapter 18 symptom code but can be assigned for both inpatient and outpatient records since the provider did not establish a more definitive diagnosis, according to sections II.A and IV.D.
Step 1: The reason for the encounter was the condition, acute
bronchitis.
Step 2: Consult the alphabetic index.
Step 3: Locate the main term “Bronchitis.”
Step 4: There is a subterm for “acute or subacute.” Additional subterms are not included in the diagnostic statement.
Step 5: Nonessential modifiers (with bronchospasm or obstruction) are terms that do not affect code assignment. Since no other subterms indented under “acute” apply here, the code listed next to this subentry—in this case J20.9—should be chosen.
Step 6: Turn to code J20.9 in the tabular list and read all instructional notes.
Step 7: The Includes note under category J20 lists alternative terms for acute bronchitis. Note that the list is not exhaustive but is only a representative selection of diagnoses that are included in the subcategory. The Excludes 1 note refers to category J40 for bronchitis and tracheobronchitis NOS. There are several conditions in the Excludes 2 notes that, if applicable, can be coded in addition to this code.
Note that the codes included in J20 represent acute bronchitis due to various infectious organisms that could be selected if identified in the documentation. In this case, the organism was not identified and there is no further division of the category past the fourth character subcategory. Therefore, code J20.9 is at the highest level of specificity.
Step 8: Review of official guideline I.C.10 provides no additional
information affecting the code selected.
Step 9: Assign code J20.9 Acute bronchitis, unspecified.
Repeat steps 1 through 9 for any concomitant diagnoses.
Step 10: In the absence of additional diagnoses that may affect
sequencing, code J20.9 should be sequenced as the first-listed, or
principal, diagnosis.
Step 1: The reason for the encounter was the condition, cerebellar ataxia.
Step 2: Consult the alphabetic index.
Step 3: Locate the main term “Ataxia.”
Step 4: Available subterms include “cerebellar (hereditary),” with additional indented subterms for “in” and “myxedema,” all essential modifiers that are included in the diagnostic statement. Two codes are provided, E03.9 and G13.2, the latter of which is in brackets.
Step 5: Note the nonessential modifier (in parentheses) after the subterm cerebellar includes the term “hereditary.” Because it is in parentheses, this term is not required in the diagnostic statement for this subentry to apply. The brackets around G13.2 identify this code as a manifestation of the condition described by code E03.9 and indicate that the two must be reported together and sequencing rules apply.
Step 6: Locate codes E03.9 and G13.2 in the tabular list, and read all instructional notes.
Step 7: For code E03.9, there are no instructional notes in the tabular list at the category E03 or code level that indicate that this condition should be coded elsewhere in the classification or that additional codes are required. Without further information from the diagnostic statement, myxedema, not otherwise specified (NOS), is appropriately reported with code E03.9 Hypothyroidism, unspecified, according to the inclusion term at this code.
Code G13.2 in the tabular list has an instructional note to “Code first underlying disease,” which includes conditions found in category E03.-. Based on this note, codes E03.9 and G13.2 are to be coded together, with G13.2 listed only as a secondary diagnosis. This correlates with what the alphabetic index indicated. As there is no further division of codes in category G13 beyond the fourth character, G13.2 is at the highest level of specificity.
Step 8: Although there are some general conventions, such as how to interpret brackets in the alphabetic index, no chapter-specific guidelines apply to this coding scenario.
Step 9: Assign codes E03.9 Hypothyroidism, unspecified, and G13.2 Systemic atrophy primarily affecting the central nervous system in myxedema. Repeat steps 1 through 9 for any concomitant diagnoses.
Step 10: Based on the alphabetic index and tabular instructional notations, code E03.9 should be sequenced as the first-listed, or principal, diagnosis followed by G13.2 as a secondary diagnosis.
Step 1: The reason for the encounter was the condition, decubitus ulcer.
Step 2: Consult the alphabetic index.
Step 3: Locate the main term “Ulcer.”
Step 4: For the subterm “decubitus,” there is no code provided or additional subterms indented, but a cross-reference is listed.
Step 5: The italicized cross-reference instructs the coder to “see Ulcer, pressure, by site.”
Repeat steps 3 through 5 for the cross-reference:
Step 3: Locate the main term “Ulcer.”
Step 4: Review the subentries for the subterm “pressure.” The next level of indent lists either the site of the ulcer or the specific stage of the ulcer (stage 1–4, unstageable, and unspecified stages). The diagnostic statement provides the site, right elbow, and the extent of tissue damage (skin loss and necrosis of subcutaneous tissue) but does not specifically state that the ulcer is stage 1, stage 2, etc. Nonessential modifiers (in parentheses) at each stage include a description of the typical extent of damage at each stage. For example, stage 1 describes “pre-ulcer skin changes limited to persistent focal edema.” Based on the documentation in the record, the coder can correlate the documentation to the nonessential modifiers and choose the specific stage from the index. The coder can also go directly to the body site, choosing the stage of the ulcer after reviewing the code options and instructional notations in the tabular list.
The diagnostic statement indicates that the extent of the damage to the elbow includes skin loss and necrosis of subcutaneous tissue, coinciding with the nonessential modifier next to the subentry “stage 3.” The body site of elbow (L89.0-) is listed as another level of indent with other body sites.
Step 5: Note that code L89.0 is followed by a dash and an
additional-character-required icon, which indicate that more characters are needed to complete the code. From here, the tabular listing for L89.0- can be consulted.
Step 6: Locate code L89.0- in the tabular list and read all instructional notes.
Step 7: The tabular listing at category L89 has an Includes note for “decubitus ulcer,” which confirms that category L89 is the appropriate category to represent what is documented in the diagnostic statement.
Several Excludes 2 notes are also listed at the category level. Excludes 2 notes represent conditions that can occur concomitantly with the decubitus ulcer and can be coded in addition to code L89, if supported by the documentation.
The subcategory codes under L89.0 indicate that the fifth character describes laterality. Locate the right elbow at subcategory L89.01. See that an additional sixth character to specify the stage of the ulcer is now needed to complete the code. The stage can be determined either by the specific documentation of the stage (e.g., stage 1, stage 2) or, in this case, a description that matches one of the inclusion terms that follow
each stage code. For example, the diagnostic description in this case of “skin loss and necrosis of the subcutaneous tissue” matches the inclusion term under L89.013 Pressure ulcer of right elbow, stage 3. No additional characters are required because code L89.013 is at its highest level of specificity.
Step 8: The official guidelines contain quite a bit of information relating to pressure ulcers in chapter-specific guideline I.C.12 as well as information in general guideline I.B.14. These and any other pertinent guidelines should be reviewed to ensure appropriate code assignment.
Step 9: Assign code L89.013 Pressure ulcer of right elbow, stage 3. Repeat steps 1 through 9 for any concomitant diagnoses.
Step 10: Since the decubitus ulcer is listed as the chief reason for the health care encounter, the first-listed, or principal, diagnosis is L89.013. However, according to the code first instructional note at the L89 category level, gangrene (I96) would be sequenced before the pressure ulcer if it were documented.
Step 1: The reason for the encounter was the condition, bimalleolar fracture.
Step 2: Consult the alphabetic index.
Step 3: Locate the main term “Fracture.” Note that many main terms represent fractures: “Fracture, burst,”“Fracture, chronic,”“Fracture, insufficiency,”“Fracture, nontraumatic NEC,”“Fracture, pathological,” and “Fracture, traumatic.” Since the diagnostic statement specifically states that this fracture was the result of trauma, the main term “Fracture, traumatic” should be used.
Step 4: Subterms that should be referenced are “ankle” and “bimalleolar (displaced),” which lists code S82.84-.
Step 5: A nonessential modifier (in parentheses) next to the term bimalleolar for “displaced” indicates that S82.84- is the default category unless the fracture is specifically identified as “nondisplaced.”
Note that code S82.84- is followed by a dash and an
additional-character icon, both of which indicate that more characters are required. From here, the tabular list can be consulted.
Step 6: Locate code S82.84- in the tabular list and read all instructional notes.
Step 7: The instructional notes at category S82 indicate that fractures not specified as displaced or nondisplaced default to displaced and that fractures not designated as open or closed default to closed. Additional instructional notes can be found at the category level but none pertain to the current scenario.
Read through the subcategory codes under S82.84, and note that the sixth character specifies displaced or nondisplaced and laterality. Based on the index nonessential modifier (displaced) and the code note at category S82, code selection should identify a displaced fracture of the right side. A displaced bimalleolar fracture of the right lower leg is coded to S82.841.
To complete the code, a seventh character must be assigned to identify the type of encounter (initial, subsequent, or sequela) and whether the fracture is open or closed. Most of the codes in category S82 require a seventh character represented in the list at the category level. However, it is important to note that some subcategories have their own specific set of seventh characters. In this instance, subcategory S82.84- does not have a unique set of seventh characters and the list provided at the category level should be used. Without documentation of the fracture being open, the tabular notation indicates that the default is closed. Character A, representing “initial encounter for closed fracture,” listed in the box at the category level is the most appropriate option.
Step 8: Assign code S82.841A Displaced bimalleolar fracture of right lower leg, initial encounter for closed fracture.
Step 9: Review chapter-specific guideline I.C.19. and any other official conventions or guidelines to ensure appropriate code assignment.
Repeat steps 1 through 9 for any concomitant diagnoses.
Step 10: Additional codes can be applied to relate the specific cause of the injury, the place of occurrence, the activity of the patient at the time of the injury, and the patient’s status, when this information is available in the record. However, coding this information is voluntary and reporting requirements depend on state mandates and/or
facility-specific reporting requirements. If assigned, the external cause codes should be reported as secondary diagnoses only with the injury (fracture) sequenced first. Most codes in chapter 20, “External Causes of Morbidity,” require a seventh character to identify the type of encounter. The seventh character assigned to an external cause code should match the seventh character of the code assigned for the associated injury or condition for the encounter.