UPDATED October 1, 2025 (October 1, 2025 - September 30, 2026)

Narrative changes appear in bold text

Items underlined have been moved within the guidelines since the April 2025, FY 2025 version

Italics are used to indicate revisions to heading changes

The Centers for Medicare and Medicaid Services (CMS) and the National Center for Health Statistics (NCHS), two departments within the U.S. Federal Government's Department of Health and Human Services (DHHS) provide the following guidelines for coding and reporting using the International Classification of Diseases, 10th Revision, Clinical Modification (ICD-10-CM). These guidelines should be used as a companion document to the official version of the ICD-10-CM as published on the NCHS website. The ICD-10-CM is a morbidity classification published by the United States for classifying diagnoses and reason for visits in all health care settings. The ICD10-CM is based on the ICD-10, the statistical classification of disease published by the World Health Organization (WHO).

These guidelines have been approved by the four organizations that make up the Cooperating Parties for the ICD-10-CM: the American Hospital Association (AHA), the American Health Information Management Association (AHIMA), CMS, and NCHS.

These guidelines are based on the coding and sequencing instructions in the Tabular List and Alphabetic Index of ICD-10-CM, but provide additional instruction. Adherence to these guidelines when assigning ICD-10-CM diagnosis codes is required under the Health Insurance Portability and Accountability Act (HIPAA). The diagnosis codes (Tabular List and Alphabetic Index) have been adopted under HIPAA for all healthcare settings. A joint effort between the healthcare provider and the coder is essential to achieve complete and accurate documentation, code assignment, and reporting of diagnoses and procedures. These guidelines have been developed to assist both the healthcare provider and the coder in identifying those diagnoses that are to be reported. The importance of consistent, complete documentation in the medical record cannot be overemphasized. Without such documentation accurate coding cannot be achieved. The entire record should be reviewed to determine the specific reason for the encounter and the conditions treated.

Only this set of guidelines, approved by the Cooperating Parties, is official.

The guidelines are organized into sections. Section I includes the structure and conventions of the classification and general guidelines that apply to the entire classification, and chapter-specific guidelines that correspond to the chapters as they are arranged in the classification. Section II includes guidelines for selection of principal diagnosis for non-outpatient settings. Section III includes guidelines for reporting additional diagnoses in non-outpatient settings. Section IV is for outpatient coding and reporting. It is necessary to review all sections of the guidelines to fully understand all of the rules and instructions needed to code properly.

The general coding guidelines provide essential instructions for proper code assignment across all healthcare settings and conditions.

A sequela is the residual effect (condition produced) after the acute phase of an illness or injury has terminated. There is no time limit on when a sequela code can be used. The residual may be apparent early, such as in cerebral infarction, or it may occur months or years later, such as that due to a previous injury.

Codes for cataclysmic events, such as a hurricane, take priority over all other external cause codes except child and adult abuse and terrorism and should be sequenced before other external cause of injury codes. Assign as many external cause of morbidity codes as necessary to fully explain each cause. For example, if an injury occurs as a result of a building collapse during the hurricane, external cause codes for both the hurricane and the building collapse should be assigned, with the external causes code for hurricane being sequenced as the first external cause code. For injuries incurred as a direct result of the hurricane, assign the appropriate code(s) for the injuries, followed by the code X37.0-, Hurricane (with the appropriate 7th character), and any other applicable external cause of injury codes. In addition to code X37.0-, Hurricane, other possible applicable external cause of morbidity codes include: W54.0-, Bitten by dog Y92.-, Place of occurrence X30.-, Exposure to excessive natural heat X31.-, Exposure to excessive natural cold, and X38.-, Flood.

For injuries that are not a direct result of the hurricane, such as an evacuee that has incurred an injury as a result of a motor vehicle accident, assign the appropriate external cause of morbidity code(s) for the injury, but do not assign code X37.0, Hurricane. If it is not clear whether the injury was a direct result of the hurricane, assume the injury is due to the hurricane and assign code X37.0-, Hurricane, as well as any other applicable external cause of morbidity codes. In addition to code X37.0-, Hurricane, assign code Y38.-, Terrorism, and any other applicable external cause of morbidity codes if the injury is the result of a terrorist event.

Z codes (other reasons for healthcare encounters) may be assigned as appropriate to further explain the reasons for presenting for healthcare services, including transfers between healthcare facilities, or provide additional information relevant to a patient encounter. The ICD-10-CM Official Guidelines for Coding and Reporting identify which codes maybe assigned as principal or first-listed diagnosis only, secondary diagnosis only, or principal/first-listed or secondary (depending on the circumstances). Possible applicable Z codes include:

The external cause of morbidity codes and the Z codes listed above are not an all-inclusive list. Other codes may be applicable to the encounter based upon the documentation. Assign as many codes as necessary to fully explain each healthcare encounter. Since patient history information may be very limited, use any available documentation to assign the appropriate external cause of morbidity and Z codes.

Specific coding instructions for this rare condition associated with breast implants.

This chapter covers diseases of the blood and blood-forming organs, as well as certain disorders involving the immune mechanism. Specific guidelines for this chapter are reserved for future expansion as coding practices evolve.

This chapter covers diseases of the ear and mastoid process. Specific guidelines for this chapter are reserved for future expansion as coding practices evolve and new clinical documentation standards emerge.

This chapter covers diseases of the digestive system, including conditions affecting the mouth, esophagus, stomach, intestines, liver, gallbladder, and pancreas. Specific guidelines for this chapter are reserved for future expansion.

Two codes are needed to completely describe a pressure ulcer: a code from category L89, Pressure ulcer, to identify the site of the pressure ulcer as well as the stage of the ulcer. The codes in category L89, Pressure ulcer, identify the site and stage of the pressure ulcer.

Codes from category L97, Non-pressure chronic ulcer of lower limb, not elsewhere classified, and category L98, Other disorders of skin and subcutaneous tissue, not elsewhere classified, are combination codes that identify the site of the non-pressure chronic ulcer as well as the severity of the ulcer. The codes in these categories identify the site and severity of the non-pressure chronic ulcer.

Codes M35.81-, Multisystem inflammatory syndrome, should be assigned for conditions documented as multisystem inflammatory syndrome and for conditions documented as pediatric inflammatory multisystem syndrome (PIMS). Assign code M35.81- when multisystem inflammatory syndrome is described as being due to COVID-19. If the condition is documented as being associated with a different infectious disease, assign the appropriate code for the infectious disease. If the infectious disease is not specified, assign code B99.8, Other infectious disease.

Code O85, Puerperal sepsis, should be assigned with a secondary code to identify the causal organism (e.g., for a bacterial infection, assign a code from category B95-B96, Bacterial infections in conditions classified elsewhere). A code from category A40, Streptococcal sepsis, or A41, Other sepsis, should not be used for puerperal sepsis. If applicable, use additional codes to identify severe sepsis (R65.2-) and any associated acute organ dysfunction.

Codes under subcategory O99.31, Alcohol use complicating pregnancy, childbirth, and the puerperium, should be assigned for any pregnancy case when a mother uses alcohol during the pregnancy or postpartum. A secondary code from category F10, Alcohol related disorders, should also be assigned to identify manifestations of the alcohol use.

A code from subcategory O9A.2, Injury, poisoning and certain other consequences of external causes complicating pregnancy, childbirth, and the puerperium, should be sequenced first, followed by the appropriate injury, poisoning, toxic effect, adverse effect or underdosing code, and then the additional code(s) that specifies the condition caused by the poisoning, toxic effect, adverse effect or underdosing.

Code O80 should be assigned when a woman is admitted for a full-term normal delivery and delivers a single, healthy infant without any complications antepartum, during the delivery, or postpartum during the delivery episode. Code O80 is always a principal diagnosis. It is not to be used if any other code from chapter 15 is needed to describe a current complication of the antenatal, delivery, or perinatal period. Additional codes from other chapters may be used with code O80 if they are not related to or are in any way complicating the pregnancy.