Diagnostic Coding – ICD-10-CM – Flashcards

HIPAA-mandated diagnosis code set under the HIPAA Electronic Health Care Transactions and Code Sets standard starting on October 1, 2014. Stands for International Classification of Diseases (ICD), Tenth Revision, Clinical Modification (CM). The ICD-10 lists diseases and codes according to a system copyrighted by the World Health Organization (WHO) of the United Nations. ICD has been revised a number of times since the coding system was developed more than one hundred years ago.

Used to code and classify morbidity data from patient medical records, physicians' offices, and surveys conducted by the National Center for Health Statistics. Codes in ICD-10-CM describe conditions and illnesses more precisely than does the WHOs ICD-10 because the codes are intended to provide a more complete picture of patients' conditions.

An ICD-10-CM diagnosis code has between 3 and 7 alphanumeric characters. The system is built on categories for diseases, injuries, and symptoms. A category has 3 characters. Most categories have subcategories of either four-character or five-character codes. Valid codes themselves are either three, four, five, six, or seven characters in length, depending on the number of subcategories provided. This variable structure enables coders to assign the most specific diagnosis that is documented in the patient medical record. When they are available for assignment in the code set, sixth and seventh characters are not optional; they must be used. The Centers for Medicare and Medicaid Services (CMS) rules state that a claim will be rejected when the most specific code available is not used. NOTE: Keep in mind that the coder can only code what is documented and cannot add to any statement in the medical record. Only the physician or health care provider can add to the statement in the medical record to clarify for coding purposes.

The National Center for Health Statistics (NCHS) and CMS release ICD-10-CM updates called addenda. It can be anticipated that many, many changes will be made during its first years of use following October 1, 2014. The major new, invalid, and revised codes are posted on the appropriate websites, such as the NCHS and CMS websites. New codes must be used as of the date they go into effect, and invalid (deleted) codes must NOT be used. The U.S. Government Printing Office (GPO) publishes the official ICD-10-CM on the Internet and in CD-ROM format every year. Various commercial publishers include the updated codes in annual coding books that are printed soon after the updates are released. The current reference must always be in use for the date of service of the encounter being coded.

There are many more categories for disease and other health-related conditions and much greater flexibility for adding new codes in the future. ICD-10-CM is a larger code set, having about 69,000 codes versus ICD-9-CM's approximately 13,000 codes. ICD-10-CM also offers a higher level of specificity and additional characters and extensions for expanded detail. There are also many more codes that combine etiology (cause) and manifestations, poisoning and external cause, or diagnosis and symptoms.

ICD-10 contains 21 chapters versus ICD-9's 17 chapters and two supplemental classifications, V codes and E codes, and there are differences in the order of chapters. Additionally, ICD-10-CM codes are alphanumeric and have five, six, or seven characters, whereas ICD-9-CM codes have three to five characters. There are two major similarities between the code sets: The two major sections of the ICD-9-CM and the ICD-10-CM code sets are the Alphabetic Index and the Tabular List.

Reference tables of related ICD-10-CM and ICD-9-CM codes. Coders may be called upon to research an ICD-9-CM code. Perhaps an old claim resurfaces, or an audit forces a review of pre-2014 codes that were reported. Workers' Compensation (WC) claims may also specify a non-ICD-10-CM code set, because WC is NOT regulated by HIPAA law and therefore is not required to use ICD-10-CM. The federal government has prepared GEMs which may be helpful in these types of situations. Both files of equivalent codes and a conversion tool may be located via an Internet search. Particularly useful is the translator tool located on the American Association of Professional Coders (AAPC) website. Note that confusion may result if the coder mixes up the ICD-9-CM codes that start with the capital letter E with those in ICD-10-CM that also start with E. There are a number of codes that are the same in both systems, but have different meanings.

The first major part is the ICD-10-CM Index to Diseases and Injuries. The major section of this part, known as the Alphabetic Index, provides an index of the disease descriptions in the second major part, the Tabular List. Many descriptions are listed in more than one manner. The second major part is the ICD-10-CM Tabular List of Diseases and Injuries. The Tabular List is made up of 21 chapters of disease descriptions and their codes.

The Neoplasm Table provides code numbers for neoplasms by anatomical site and is divided by the description of the neoplasm.

The Table of Drugs and Chemicals provides an index in table format of drugs and chemicals that are listed in the Tabular List.

The Index to External Causes provides an index of all the external causes of diseases and injuries that are listed in the related chapter of the Tabular List.

As always, the first step in the coding process begins with the physician's diagnostic statement, which contains the medical term describing the condition for which a patient is receiving care. For each encounter, this medical documentation includes the main reason for the patient encounter. It may also provide descriptions of additional conditions or symptoms that have been treated or that are related to the patient's current illness.

The coder begins with looking up the medical term that describes the patient's condition based on the physician's diagnostic statement. The coder locates the description/code in the Alphabetic Index and then verifies the proposed code selection by checking it in the Tabular List and studying its entries. In each part of ICD-10-CM (the Alphabetic Index and the Tabular List), conventions (typographic techniques that provide visual guidance for understanding information, help coders understand the rules and select the right code. The primary rule is that BOTH the Alphabetic Index and the Tabular list MUST be used sequentially to pick a code. This process MUST be followed when assigning all codes.

The hyphen means that the coder will need to drill down within a list and select the right code. For example, if the code H66.9- is indicated, the coder must select one of the codes listed under this code which are H66.90, H66.91, H66.92, and H66.93, based on the physician's documentation within the patient's medical record.

Part of the ICD-10-CM listing disease and injuries alphabetically with corresponding diagnosis codes. The Alphabetic Index contains all the medical terms in the Tabular List classifications. For some conditions, the Alphabetic Index also lists common terms that are NOT found in the Tabular List. The Alphabetic Index is organized by CONDITION, not by the body part (anatomical site) in which it occurs. For example, the term "wrist fracture" is located by looking under "fracture" (the condition) and then, below it, "wrist" (the location). The Alphabetic Index has three additional sections: (1) the Neoplasm Table; (2) the Table of Drugs and Chemicals; and (3) the Index to External Causes.

Part of ICD-10-CM listing diagnosis codes in chapters alphanumerically.

Physician's description of the main reason for the patient's encounter.

Typographic technique that provides visual guidance for understanding information.

A word that identifies a disease or condition in the Alphabetic Index. Each main term appears in boldface type and is followed by its default code, the one most frequently associated with it. For example, if the physician's diagnostic statement in the patient's medical record is "the patient presents with blindness," the main term is "blindness" and is located in the Alphabetic Index with a default code of H54.0.

A word or phrase that descries a main term in the Alphabetic Index. Below each main term, any subterms with their codes appear. Subterms are essential in the selection of correct codes. They may show the etiology (cause or origin) of the disease, or describe a particular type or body site for the main term. For example, the main term "blindness" has 21 subterms, each of which indicates a different etiology or type for that condition.

Cause or origin of a disease or condition.

A supplementary word or phrase that helps define a code in ICD-10-CM. Nonessential modifiers for main terms or subterms are shown in parentheses on the same line as the main term. Nonessential modifiers are supplementary terms that are NOT essential to the selection of the correct term. They help point to the correct term, but they do not have to appear in the physician's diagnostic statement for the coder to correctly select the code.

Many terms appear more than once in the Alphabetic Index. Often, the term in common use is listed, as well as the accepted medical terminology. For example, there is an entry for "flu", with a cross-reference to "influenza."

An eponym is a name or phrase formed from or based on a person's name. An eponym is a condition (or a procedure) named for a person, such as the physician who discovered or invented it; or a patient who may have been the first to be diagnosed with a condition. An eponym is usually listed both under that name and under the main term "disease" or "syndrome." For example, Hodgkin's disease appears as a main term and as a subterm under the main term "disease."

A group of symptoms that together are characteristic of a specific disorder, disease, or the like. The Alphabetic Index is the guide for coding syndromes, such as battered child syndrome or HIV infection. If the syndrome is not identified, its manifestations (an obvious indication or specific evidence that a disease is present; a symptom or symptoms; characteristic sign or symptom of a disease) are assigned codes.

If the main term or subterm is too long to fit on one line, as may be the case when many nonessential modifiers appear, turnover or carryover lines are used. Turnover lines are always indented farther to the right than are subterms. It is important to read carefully to distinguish a turnover line from a subterm line. Without close attention, it is possible to confuse a turnover entry with a subterm entry.

If the cross-reference "see" appears after a main term, the coder MUST look up the term that follows the word "see" in the index. the "see" reference means that the main term where the coder first looked is NOT correct; another category must be used. "See" cross-references direct a coder to another term. "See also" is another type of cross-reference and points the coder to additional, related index entries. "See also category" cross-references indicates that the coder should review the additional categories that are mentioned. For example, if you look under "Blind", you will see (see also Blindness) which directs the coder to check "Blindness" as well as "Blind."

The abbreviation NEC indicates the code to use when a disease or condition cannot be placed in any other category. NEC appears with a term when there is no code that is specific for the condition. NEC means that no code matches the exact situation.

Indicates the code to use when no information is available for assigning the disease or condition a more specific code; unspecified. NOS indicates the code to use when a condition is not completely described.

Characteristic sign or symptom of a disease.

Some conditions may require two codes, one for the etiology (cause) and a second for the manifestation, the disease's typical signs, symptoms, or secondary processes. This requirement is indicated when two codes, the second in brackets [ ], appear after a term. For example Pneumonia in rheumatic fever I00 [J17]. This entry indicates that the diagnostic statement "pneumonia in rheumatic fever" requires two codes, one for the etiology (rheumatic fever, I00) and one for the manifestation (pneumonia, J17). The code J17, because it appears in brackets, must be listed after the code I00. Multiple codes are required when two codes, the second in brackets, appear after a main term.

The use of brackets in the Alphabetic Index around a code means that it cannot be the first-listed code in coding that particular diagnostic statement. The code(s) in brackets must be listed after the codes for the etiology.

The use of connecting words such as "due to," "during," "following," and "with" may also indicate the need for two codes or for a single code that covers both conditions.

Single code describing both the etiology and the manifestation(s) of a particular condition. When the Alphabetic Index indicates the possible need for two codes, the Tabular List entry is used to determine whether in fact both would be needed. In some cases, a combination code that describes both the etiology and manifestation is available instead of two codes. Combination codes may also exist that classify two diagnoses or one diagnoses with an associated complication.

The diseases and injuries in the Tabular List are organized into chapters according to etiology, body system, or purpose. The 21 chapters are listed from A00 to Z99 (except for the letter "U".)

A category is a three-character alphanumeric code that covers a single disease or related condition. For example, the category L03 covers cellulitis and acute lymphangitis.

Four-character or five-character alphanumeric subdivision of a category code. A subcategory provides a further breakdown of a disease to show its etiology, site, or manifestation. For example, the LO3 category has six subcategories: L03.0, L03.1, L03.2, L03.3, L03.8, L03.9.

A code is the smallest division and has either 3, 4, 5, 6, or 7 alphanumeric characters. Note that the first character in a code is always a letter. The complete alphabet, except for the letter "U" is used. The second and third characters in a code may be either numbers or letters, although currently the second character is usually (but not always) a number. A valid code has to have at least three characters. If it has more than that, a period is placed following the third character. Each character beyond the category level provides greater specificity to the code's meaning.

Character "x" inserted in a code to fill a blank space. The placeholder character is also known as the "dummy placeholder" designated as "x" in some codes when a fifth, sixth, or seventh digit character is required, but the digit space to the left of that character is empty. For example, the subcategory T46.1 Poisoning by, adverse effect of and underdosing of calcium-channel blockers, uses the SIXTH digit to describe whether the poisoning was accidental (unintentional), intentional self-harm, caused by assault, undetermined, or related to an adverse effect or underdosing. Since there is no fifth digit assigned, an "x" is used to hold that fifth place and we would use T46.1x2 Poisoning by calcium-channel blockers, intentional self-harm.

ICD-10-CM requires assigning a seventh character in some categories -- to specify the sequence of the visit (EX: initial encounter for the problem), or the subsequent encounter for the problem; or sequela, (the problem results from a previous disease or injury.) An extension requirement is contained in a note at the start of the codes it covers. The seventh character must always be in position 7 of the code, so if the code is not at least six characters long, the placeholder character "x" must be used to fill the empty space. For example, for subcategory S64.22, Injury of radial nerve at wrist and hand level of left arm, initial encounter -- there is no sixth digit but requires the seventh, so the correct code for an initial encounter would be S64.22xA (where the seventh digit A is for initial encounter.)

Inclusion Notes are headed by the word "includes" and refine the content of the category appearing above them. These are Tabular List entries addressing the applicability of certain codes to specified conditions.

Tabular list entry limiting applicability of particular codes to specified conditions. Exclusion notes are headed by the word "excludes" and indicate conditions that are not classifiable to the code above. Two types of exclusion notes are listed. Excludes 1 is used when two conditions could not exist together, such as an acquired and a congenital condition; it means "not coded here." Excludes 2 means "not included here" but a patient could have both conditions at the same time. The note may also give the code(s) of the excluded condition(s).

A colon (:) indicates an incomplete term. One or more of the entries following the colon is required to make a complete term. Unlike terms in parentheses or brackets, when the colon is used, the diagnostic statement MUST include one of the terms after the colon to be assigned a code from the particular category.

Parentheses ( ) are used around descriptions that do NOT affect the code -- that is, nonessential, supplementary terms.

Brackets [ ] are used around synonyms, alternative wordings, or explanations. They have the same meaning as parentheses.

NEC and NOS are used in the Tabular List with the same meanings as in the Alphabetic Index.

The convention that addresses multiple codes for conditions that have both an underlying etiology (cause) and manifestations (symptoms) is indicated in the Tabular List by some phrases that contain instructions about the need for additional notes. The phrases point to situations in which more than one code is required. For example, a statement that a condition is "due to" or "associated with" may require an additional code.

The etiology code may be followed by the instruction "use additional code" or a note saying the same. The order of the codes must be the same as shown in the Alphabetic Index: the etiology comes first, followed by the manifestation code.

The instruction "code first underlying disease" (or similar wording) appears below a manifestation code that must NOT be used as a first-listed code. These codes are for symptoms only, never for causes. At times, a specific instruction is given. For example, F07 Personality and behavioral disorders due to known physiological condition -- "code first the underlying physiological condition."

The "use additional code" note also appears when ICD-10-CM requires assignment of codes for health factors such as tobacco use and alcohol use.

Use of ICD-10-CM classification system to capture the side of the body that is documented; the fourth, fifth, or sixth characters of a code specify the affected side(s), such as right arm, left wrist, both eyes. When the affected side of the condition is not known, an unspecified code is assigned. If a condition is documented as bilateral but there is no appropriate code for bilaterality (that is, both), two codes for the left and right sides are assigned.

ICD-10-CM code for an external cause of a disease or injury. Codes in Chapter 20 of ICD-10-CM classify external cause codes, which report the cause of injuries from various environmental events, such as transportation accidents, falls, and fires. External cause codes are NOT used alone or as first-listed codes. They always supplement a code that identifies the injury or condition itself. Many blocks of accident and injury codes in Chapter 20 require additional external cause codes for: (1) the encounter, A = initial, D = subsequent, or S = sequela; (2) the place of occurrence, category Y92; (3) the activity, category Y93; and (4) the status, category Y99. External cause codes are located by first using the third section of the Alphabetic Index, Index to External Causes. This index is organized by main terms describing the accident, circumstance, or event that caused the injury. Codes are verified in Chapter 20 of the Tabular List. External cause codes are often used in collecting public health information. They capture cause, intent, place, and activity. As many external cause codes as are needed to describe these factors should be reported. Note, that these codes are NOT needed IF the external cause and intent are already included in a code from another chapter.

Abbreviation for ICD-10-CM codes that identify factors that influence health status and encounters that are not due to illness or injury. Chapter 21 contains Z codes that are used to report encounters for circumstances other than a disease or injury, such as factors influencing health status, and to describe the nature of a patient's contact with health services. There are two main types: (1) reporting visits with healthy (or ill) patients who receive services other than treatments, such as annual checkups, immunizations, and normal childbirth. This use is coded by a Z code that identifies the service, such as Z00.01 Encounter for general adult medical examination with abnormal findings; and (2) Reporting encounters in which a problem not currently affecting the patient's health status needs to be noted, such as personal and family history. For example, a person with a family history of breast cancer is at higher risk for the disease, and a Z code is assigned as an additional code for screening codes to explain the need for a test or procedure such as Z80.3 Family history of malignant neoplasm of breast. Use Z codes to show medical necessity. Z codes such as family history or a patient's previous condition help demonstrate why a service was medically necessary. A Z code can be used as EITHER a primary code for an encounter or as an additional code. It is researched in the same way as other codes, using the Alphabetic Index to point to the term's code and the Tabular List to verify it. The terms that indicate the need for Z codes, are NOT the same as other medical terms. They usually have to do with a reason for an encounter other than a disease or its complications. When found in diagnostic statements the words "contact/exposure," "contraception," "counseling," "examination," "fitting of," "follow-up," "history (of)," "screening/test," "status," "supervision (of)," or "vaccination/inoculation" often point to Z codes.

General rules, inpatient (hospital) coding guidance, and outpatient (physician office/clinic) coding guidance from the four cooperating parties (CMS advisers and participants from the AHA, AHIMA, and NCHS). Section I covers conventions, general coding guidelines, and chapter-specific guidelines by first reviewing the Alphabetic Index and Tabular List conventions and broad coding rules, and then discusses key topics affecting the use of codes in each of the 21 chapters. Section II covers selection of principal diagnosis. Section III covers reporting additional diagnoses, explaining the guidelines for establishing the diagnosis or diagnoses for inpatient cases. Section IV covers diagnostic coding and reporting guidelines for outpatient services, explaining the guidelines for establishing the diagnosis or diagnoses for all outpatient encounters. The key points from this section are summarized as: (1) code the primary diagnosis first, followed by current coexisting conditions; (2) code to the highest level of certainty; and (3) code to the highest level of specificity.

The reasons for patient encounters are often "acute" symptoms -- generally, relatively sudden or severe problems. Acute conditions are coded with the specific code that is designated acute, if listed. Many patients receive ongoing treatment for "chronic" conditions -- those that continue over a long period of time or recur frequently. For example, a patient may need a regular injection for the management of rheumatoid arthritis. In such cases, the disease is coded and reported for as many times as the patient receives care for the condition. In some cases, an encounter covers both an acute and a chronic condition. Some conditions do not have separate entries for both manifestations, so a single code applies. If both the acute and the chronic illnesses have codes, the ACUTE code is listed FIRST and the chronic code is listed next.

Conditions that remain after an acute illness or injury has been treated and resolved. Often called residual effects or late effects, some happen soon after the disease is over, and others occur later. The diagnostic statement may state: (1)"Due to an old..." such as swelling due to old contusion of knee; (2) "Late..." such as nausea as a late effect of radiation sickness; (3) "Due to a previous..." such as abdominal mass due to a previous spleen injury; or (4) "Traumatic" such as including scarring or nonunion of a fracture or malunion of fracture, left humerus. In general, the main term "sequela" is followed by subterms that list the causes. Two codes are usually required. First reported is the code for the specific effect, (such as muscle soreness), followed by the code for the cause, (such as the late effect of rickets). The code for the acute illness that led to the sequela is NEVER used with a code for the late effect itself.

Diagnoses are not always established at a first encounter with the patient. Follow-up visits over time may be required before the physician determines a primary diagnosis. During this process, although possible diagnoses may appear in the physician's documentation as diagnostic work is progressing, these inconclusive diagnoses are NOT used to determine the codes reported for reimbursement of service fees.

Instead of inconclusive diagnoses, the specific signs and symptoms are coded and reported. A "sign" is an objective indication that can be evaluated by a physician, such as weight loss. A "symptom" is a subjective statement by the patient that cannot be confirmed during an examination, such as pain.

Possible, but not confirmed, diagnoses, such as those preceded by "rule out," "suspected," "probable," or "likely," are NOT coded in the outpatient (physician practice) setting. In the inpatient setting, the guidance is different. For hospital coding, the first-listed diagnosis is referred to as the "principal diagnosis" and is defined as the condition established after study to be chiefly responsible for the admission. "After study" means at the patient's discharge from the facility. If a definitive condition has not been established, then, at discharge, the inpatient coder codes the condition that matches the planned course of treatment most closely as if it were established.

Surgery is coded according to the diagnosis that is listed as the reason for the procedure. In some cases, the postoperative diagnosis is available and is different from the physician's primary diagnosis before the surgery. If so, the postoperative diagnosis is coded because it is the highest level of certainty available. For example, if an excisional biopsy is performed to evaluate mammographic breast lesions or a lump of unknown nature, and the pathology results show a malignant neoplasm, the diagnosis code describing the site and nature of the neoplasm is used.

The more characters a code has, the more specific it becomes; the additional characters add to the clinical picture of the patient. Using the most specific code possible is referred to as coding to the highest level of specificity. NOTE: You can NEVER use a code that states information that is NOT included in the physician's statement. For example, having an HIV test is vastly different from being diagnosed as having HIV. Therefore, you only ever code information that you have in the diagnostic statement and you NEVER EVER guess or add to what is provided by the physician or health care provider!

In the Tabular List, the coder may need to choose between a code described as the core condition, "other (or other unspecified) versus unspecified." For example L70.8 Other acne or L70.9 Acne unspecified. If the documentation mentions a type or form of the condition that is not listed, the coder chooses "other," because a type is indicated but not found. If no type is mentioned, the documentation is not complete enough to assign a more specific code, and so the least-specific choice, "unspecified," is assigned. If there is no other versus unspecified coding option, select the "other specified" which in this situation represents both "other" and "unspecified."

The correct procedure for assigning accurate diagnosis codes has six steps: (1) Review complete medical documentation; (2) abstract the medical conditions from the visit documentation; (3) identify the main term for each condition; (4) locate the main term in the Alphabetic Index; (5) verify the code in the Tabular List; and (6) check compliance with any applicable Official Guidelines and list codes in appropriate order.

Step 1 involves reviewing complete medical documentation. In outpatient settings, diagnosis coding begins with the patient's chief complaint (CC). The chief complaint is the medical reason that the patient presents for a particular visit, as well as the duration of the medical reason. The physician then examines the patient and evaluates the condition or complaint, documenting the diagnosis, condition, problem, or other reason that the documentation shows as being chiefly responsible for the services that are provided. This primary diagnosis provides the main term to be coded first. Documentation will also mention any coexisting complaints that should be coded. If a patient has cancer, the disease is probably the patient's major health problem. However, if that patient sees the physician for an ear infection that is NOT related to the cancer, the primary diagnosis for that particular claim is the ear infection.

Step 2 involves abstracting the medical conditions from the visit documentation. The code will be assigned based on the physician's diagnosis or diagnoses. This information may be located on the encounter form or elsewhere in the patient's medical record, such as in a progress note. For example, a medical record may read: CC: Chest and epigastric pain; feels like a burning inside for 10 days. Occasional reflux. Abdomen soft, flat without tenderness. No bowel masses or organomegaly. Dx: Peptic ulcer. The diagnosis (Dx) is peptic ulcer.

Step 3 involves identifying the main term for each condition. If needed, decide which is the main term or condition of the diagnosis. For example, if the diagnosis is peptic ulcer, the main term or condition is ulcer. The word peptic describes what type of ulcer it is. Other diagnosis examples: (1) complete paralysis -- paralysis is the main term and the supplementary term is complete; (2) heart palpitation -- the main term is palpitation and the supplementary term is heart; (3) Panner's disease -- the coder can look up either disease as the main term, followed by Panner's, or by looking up Panner's disease.

Step 4 involves locating the main term in the Alphabetic Index. The following guidelines should be observed in choosing the correct term: (1) use any supplementary terms in the diagnostic statement to help locate the main term; (2) read and follow any notes below the main term; (3) review the subterms to find the most specific match to the diagnosis; (4) read and follow any cross-references; and (5) make note of a two-code (etiology and/or manifestation) indication.

Step 5 involves verifying the code from the Alphabetic Index in the Tabular List. The following guidelines are observed to verify the selection of the correct code: (1) read "includes" or "excludes" notes, checking back to see if any apply to the code's category, section, or chapter; (2) be alert for and follow instructions for fifth-digit requirements; (3) follow any instructions requiring the selection of additional codes (such as "code also" or "code first underlying disease"; and (4) list multiple codes in correct order.

Step 6 involves checking compliance with any applicable Official Guidelines and listing codes in appropriate order. Coders should be sure not to include suspected conditions (for outpatient settings) and to report the primary diagnosis code, followed by any coexisting conditions and external source codes.