The official 2011 guidelines for coding and reporting ICD-10 diagnosis codes are provided by The Centers for Medicare and Medicaid Services (CMS) and the National Center for Health Statistics (NCHS); these departments are within the Department of Health and Human Services (DHHS).
The ICD-10 guidelines can be referenced on the Centers for Disease Control website.
These guidelines are a set of rules giving guidance on how to code encounters using official conventions, notes, and sequencing priority. There are coding rules that apply to the Alphabetic Index and the Tabular list. The Health Insurance Portability and Accountability Act (HIPAA) requires adherence to the guidelines when assigning diagnosis codes for inpatient and outpatient encounters. It is important to note that the chapter instructions take precedence over the official guidelines because the official guidelines serve to accompany and complement instructions given within the ICD-10 itself.
The guideline sections
The guidelines are organized into sections. Section 1A describes the conventions used in ICD-10-CM to include format and structure, placeholder character, 7th character and abbreviations. The abbreviations are similar to ICD-9; for example: “NOS” and “NEC”. Punctuation such as brackets, parenthesis, and colons are unchanged from ICD-9-CM diagnosis coding. You will still find “includes”, and “Excludes” notes but there is a distinct difference in the application of the “excludes” notes. In ICD-10, Excludes 1 is a pure excludes note. It means “not coded here” and the code excluded should never be coded at the same time as the code above the Excludes 1 note. An “Excludes 2” note represents “not coded here” and the condition with this note is not part of the referenced code above the note. The patient may have both conditions at the same time and in this case it would be acceptable to assign both the code and the excluded 2 condition together. Section 1A also defines the use and sequencing of multiple codes with an Etiology/manifestation convention (“code first”, “use additional code”, and “in diseases classified elsewhere” notes).
Section 1B of the official guidelines gives general coding instructions for locating a code in ICD-10-CM that corresponds to a diagnosis or reason for visit. The level of detail is discussed and emphasizes that diagnosis codes are to be used and reported at their highest number of digits available (3, 4, 5, 6, or 7). Each unique ICD-10 code may be reported only once for an encounter. Section 1B also gives instructions for coding laterality, late effects (sequela), and documenting BMI and pressure ulcer stages.
Section 1C describes chapter-specific coding guidelines beginning with Chapter 1, Certain Infectious and Parasitic Diseases (A00-B99), and ending with Chapter 21, Factors Influencing Health Status and Contact with Health Services (Z00-Z99). Chapter 21 replaces the “V” codes in ICD-9 classification.
Section II (A-J) has guidelines for selection of the principal diagnosis assignment. This includes two or more diagnoses, signs and symptoms, complications, admission from observation or outpatient surgery. It is important to read all section guidelines before attempting code assignment.
Section III (A-C) contains rules for other additional diagnosis. This includes rules for coding previous conditions, abnormal findings and uncertain diagnosis. The rules for “uncertain diagnosis” such as “probable”, “suspected”, “likely”, “questionable”, “possible”, or “still to be ruled out”, differ by place of service. The guideline states “code the condition as if it existed or was established”, but, it is applicable only to inpatient admissions to short-term, acute, long-term care and psychiatric hospitals.
Section IV (A-Q) guidelines are for diagnostic coding and reporting for outpatient services. Selection of first-listed condition and accurate reporting for outpatient diagnosis codes, signs and symptoms, chronic conditions and level of detail are discussed. This section covers rules for coding diagnostic services only, therapeutic services only, preoperative evaluations, ambulatory surgery, routine outpatient prenatal visits, encounters for general medical examinations with abnormal findings, and, routine health screenings.
The alphabetic index includes the Index to diseases and injuries, Table of neoplasms, Table of drugs and chemicals, and, the External cause index. The coding process begins with the Alphabetic index. The alphabetic index in ICD-10-CM is formatted the same way as the Index in ICD-9-CM. Main code descriptor terms are listed in alphabetic order, in bold type. Then, indented beneath the main term, any applicable additional qualifiers, descriptors, or modifying terms will be shown, in their own alphabetic list.
There are some interesting codes in the tabular list. An example is R99, Ill-Defined and Unknown Cause of Mortality. This code is used in very limited circumstances when a patient who has already died is brought into an emergency room or other healthcare facility and is pronounced dead on arrival. It does not represent the discharge disposition of death.
When reporting “falls” it is necessary to determine the circumstances around that statement. For example, Repeated falls, code R29.6, is for use for encounters when a patient has recently fallen and the reason for the fall is being investigated. But, code Z91.81, History of falling, is for use when a patient has fallen in the past and is at risk for future falls. When appropriate, both codes R29.6 and Z91.81 may be assigned together.
The ICD-10-CM makes a distinction between burns and corrosions. The burn codes are for thermal burns, except sunburns, that come from a heat source, such as a fire or hot appliance. The burn codes are also for burns resulting from electricity and radiation. Corrosions are burns due to chemicals. The guidelines are the same for burns and corrosions, but separate ICD-10 codes describe a burn or corrosion.
Nancy Maguire, ACS, PCS, FCS, HCS-D, CRT, author of The Nancy Maguire GPS to ICD-10-CM Planning and Implementation Guide, is a nationally-renowned procedural and diagnostic coding instructor, bootcamp trainer, and workshop leader. She has spent more than 30 years as a hands-on coder and has authored countless coding articles and presentations. In her expansive career, she has transitioned from nursing, to coding, to practice management, auditing and consulting. Nancy served as Director of Coding and Reimbursement at UTMB in Galveston Texas for four years. She served the first two terms as president of AAPC in the early 1990s.
Hear Nancy speak in two complimentary archived webinars on ICD-10 presented by Kareo medical billing software: How to Prepare for ICD-10/5010 to Reduce F41.1 (Anxiety Reaction) or Preparing for ICD-10-CM: The Nitty-Gritty of Diagnosis Coding.