See What’s New for ICD-10-CM 2021

Make sure your diagnosis coding is up to date by reviewing
this chapter-by-chapter summary of the changes effective October 1.

The future is here, and it brought diagnosis codes for hoverboard accidents. But that’s not all that’s changed in ICD-10-CM 2021, effective Oct. 1, 2020, through Sept. 30, 2021.

Below are highlights from the 56-page ICD-10-CM Tabular List of Diseases and Injuries 2021 Addenda. We’ll focus mostly on codes, so be sure to check for note and instruction updates in the official code set as you dig deeper into the changes that affect you.

CHAPTER 1  Certain Infectious and Parasitic Diseases (A00-B99)

The first new codes in ICD-10-CM 2021 are A84.81 Powassan virus disease and A84.89 Other tick-borne viral encephalitis. There are five more new codes under protozoal disease subcategory B60.0- Babesiosis.

The addenda file also shows an Excludes1 note for COVID-19 (U07.1) under B34.2 Coronavirus infection, unspecified. This note and other changes related to COVID-19 were effective April 1, 2020, but this is the first annual update to include those changes.

CHAPTER 2  Neoplasms (C00-D49)

Along with correcting typos, Chapter 2 references a new code in a note under C93.1- Chronic myelomonocytic leukemia: “Code also, if applicable, eosinophilia (D72.18).”

CHAPTER 3 Diseases of the Blood and Blood-Forming Organs and Certain Disorders Involving the Immune Mechanism (D50-D89)

This chapter includes a longer list of updates than almost any other chapter. Many relate to D57.- Sickle-cell disorders, which features more than 20 new codes, from D57.03 Hb-SS disease with cerebral vascular involvement to D57.818 Other sickle-cell disorders with crisis with other specified complication.

New codes under D59.1- Other autoimmune hemolytic anemias provide choices for warm, cold, and mixed types. Subcategory D72.1- Eosinophilia also adds more specific options such as D72.11- Hypereosinophilic syndrome [HES] and (the code mentioned in the Chapter 2 note) D72.18 Eosinophilia in diseases classified elsewhere.

Other changes include new codes under D84.8- Other specified immunodeficiencies for immunodeficiencies due to other conditions, drugs, and external causes, and new codes under D89.83- Cytokine release syndrome that allow you to specify the grade (1 to 5).

CHAPTER 4  Endocrine, Nutritional and Metabolic Diseases (E00-E89)

The biggest changes in Chapter 4 include new codes for rare inherited disorders: E70.81 Aromatic L-amino acid decarboxylase deficiency and E74.810 Glucose transporter protein type 1 deficiency.

CHAPTER 5  Mental, Behavioral and Neurodevelopmental Disorders (F01-F99)

Chapter 5 adds many codes for substance use and abuse with withdrawal. Providers should document withdrawal delirium and withdrawal with perceptual disturbance, when present, to help with code selection. New codes range from F10.130 Alcohol abuse with withdrawal, uncomplicated to F19.139 Other psychoactive substance abuse with withdrawal, unspecified.

CHAPTER 6  Diseases of the Nervous System (G00-G99)

The numerous changes in Chapter 6 relate primarily to new codes in these areas:

  • G11.1- Early-onset cerebellar ataxia, including a code for Friedreich ataxia
  • G40.- Epilepsy and recurrent seizures, with new codes for cyclin-dependent kinase-like 5 deficiency disorder and Dravet syndrome
  • G71.2- Congenital myopathies, with more detailed options for nemaline and centronuclear myopathies
  • G96.0- Cerebrospinal fluid leak, where the key terms are spontaneous, cranial, and spinal
  • G96.1- Disorders of meninges, not elsewhere classified, including an option for perineural cyst
  • G96.81- Intracranial hypotension, with coding based on unspecified, spontaneous, or other
  • G97.8- Other intraoperative and postprocedural complications and disorders of nervous system, including two new codes for intracranial hypotension following procedures

CHAPTER 7  Diseases of the Eye and Adnexa (H00-H59)

ICD-10-CM changes for eye care often involve adding codes for laterality, and the 2021 code set is no exception. There are 28 new codes allowing you to specify right, left, bilateral, or unspecified eye for various diagnoses under H18.5- Hereditary corneal dystrophies. Chapter 7 also adds H55.82 Deficient smooth pursuit eye movements.

CHAPTER 9  Diseases of the Circulatory System (I00-I99)

The addenda do not show any changes for Chapter 8: Diseases of the Ear and Mastoid Process (H60-H95), but Chapter 9 has one of the longer lists of changes.

The bulk of the additions are Includes notes for existing codes under I70.- Atherosclerosis. The notes state the codes apply to chronic limb-threatening ischemia and critical limb ischemia. The ICD-10-CM Index to Diseases and Injuries has pages of updates related to these terms, as well.

CHAPTER 10 Diseases of the Respiratory System (J00-J99)

The changes in Chapter 10 clarify when it’s appropriate to report codes for influenza and respiratory infections together. In 2020, the J00-J06 block, Acute upper respiratory infections, had this note: Excludes1: influenza virus with other respiratory manifestations (J09.X2, J10.1, J11.1).

In 2021, that note no longer applies to the complete block. Now the Excludes1 note is under only specific codes and categories such as J00 Acute nasopharyngitis [common cold].

In an important change, J04.- Acute laryngitis and tracheitis and J05.- Acute obstructive laryngitis [croup] and epiglottitis added a Code also note for:

  • influenza due to identified novel influenza A virus with other respiratory manifestations (J09.X2)
  • influenza due to other identified influenza virus with other respiratory manifestations (J10.1)
  • influenza due to unidentified influenza virus with other respiratory manifestations (J11.1)

Another notable change in this chapter is new subcategory J82.8- Pulmonary eosinophilia, not elsewhere classified. It includes separate codes for chronic and acute eosinophilic pneumonia and eosinophilic asthma. This chapter updates J84.17- Other interstitial pulmonary diseases with fibrosis in diseases classified elsewhere, as well, to add a unique code for the progressive fibrotic phenotype.

CHAPTER 11  Diseases of the Digestive System (K00-K95)

To choose from new Chapter 11 codes under K20.- Esophagitis and K21.0- Gastro-esophageal reflux disease with esophagitis, you need to check for documentation of bleeding.

Diverticulitis subcategories that include “with perforation and abscess” (K57.0-, K57.2-, K57.4-, K57.8-) have an update, too. They no longer have inclusion notes for diverticulitis with peritonitis. The note to “Code also if applicable peritonitis K65.-” is still present under K57.- Diverticular disease of intestine.

Also watch for new codes under K74.0- Hepatic fibrosis with specific options for early (stage F1 or F2) and advanced (stage F3).

CHAPTER 12  Diseases of the Skin and Subcutaneous Tissue (L00-L99)

There are two note changes in Chapter 12:

Under L57.- Skin changes due to chronic exposure to nonionizing radiation, the 2021 code set adds the bolded language: Use Additional code to identify the source of the ultraviolet radiation (W89), or other nonionizing radiation (W90).

Under L98.4- Non-pressure chronic ulcer of skin, not elsewhere classified, the Excludes2 note for varicose ulcer corrects the code range from I83.0-I82.2 to I83.0-I83.93.

CHAPTER 13  Diseases of the Musculoskeletal System and Connective Tissue (M00-M99)

In Chapter 13, all the categories below have new codes with “other specified site” in the descriptor:

M05.-    Rheumatoid arthritis with rheumatoid factor

M06.-    Other rheumatoid arthritis

M08.-    Juvenile arthritis

M19.-    Other and unspecified osteoarthritis

M24.-    Other specific joint derangements

Continuing the “other” trend, M24.- also includes new codes for “other specified joint,” as does M25.- Other joint disorder, not elsewhere classified. Subcategory M80.0- Age-related osteoporosis with current pathological fracture has two new codes for “other site.”

Chapter 13 also adds unique codes for right, left, bilateral, and unspecified in these subcategories:

M26.64-    Arthritis of temporomandibular joint

M26.65-    Arthropathy of temporomandibular joint

M92.5- Juvenile osteochondrosis of tibia and fibula

Subcategory M92.5- also has important revisions at the five-character level. For instance, M92.51 represented the right leg tibia and fibula in 2020, but in 2021 it’s a subcategory defined as Juvenile osteochondrosis of proximal tibia.

CHAPTER 14  Diseases of the Genitourinary System (N00-N99)

In the N00-N08 Glomerular diseases block, almost every category has a new, unique code for “with C3 glomerulonephritis.” An example is N00.A Acute nephritic syndrome with C3 glomerulonephritis.

Subcategory N18.3- Chronic kidney disease, stage 3 (moderate) is expanded with new options for stages 3a, 3b, and 3 unspecified. Subcategory N61.2- Granulomatous mastitis is also expanded with additions for unspecified, right, left, and bilateral breast involvement.

CHAPTER 15  Pregnancy, Childbirth and the Puerperium (O00-O9A)

There are five new codes in this chapter. Two of the codes (O34.218 and O34.22) relate to maternal care for cesarean scars. The other three result from expanding O99.89- Other specified diseases and conditions complicating pregnancy, childbirth and the puerperium to offer one code each for pregnancy, childbirth, and the puerperium.

CHAPTER 16  Certain Conditions Originating in the Perinatal Period (P00-P96)

The biggest update in this chapter is the addition of subcategory P91.82- Neonatal cerebral infarction. The subcategory includes four codes, allowing you to specify the side as right, left, bilateral, or unspecified.

CHAPTER 17  Congenital Malformations, Deformations and Chromosomal Abnormalities (Q00-Q99)

Revisions to Q51.2- Other doubling of uterus make up most of the changes to Chapter 17. For instance, ICD-10-CM 2021 deletes Q51.20 Other doubling of uterus, unspecified and revises Q51.28 from Other doubling of uterus, other specified to Other and unspecified doubling of uterus.

CHAPTER 18  Symptoms, Signs and Abnormal Clinical and Laboratory Findings, Not Elsewhere Classified (R00-R99)

Many coders probably have memorized R51 Headache, but R51 is not a reportable code in the 2021 code set. Instead, use one of these new four-character codes:

R51.0     Headache with orthostatic component, not elsewhere classified

                Headache with positional component, not elsewhere classified

R51.9     Headache, unspecified

                     Facial pain NOS

This section also changes the Excludes1 note to Excludes2 for atypical face pain (G50.1), migraine and other headache syndromes (G43-G44), and trigeminal neuralgia (G50.0).

Another noteworthy change in this chapter is the expansion of R74.0- Nonspecific elevation of levels of transaminase and lactic acid dehydrogenase [LDH]. In 2021, there is one code for liver transaminase levels (R74.01) and another for LDH (R74.02).

CHAPTER 19  Injury, Poisoning, and Certain Other Consequences of External Causes (S00-T88)

The first major change in this chapter is the addition of 18 six-character options under S20.- Superficial injury of thorax that allow you to identify bilateral front wall and middle front wall injuries. Keep in mind that each code in S20.- requires a 7th character (A, D, or S), so each six-character addition in the addenda translates to three new seven-character codes.

The next big change is more specific options under T40.4- Poisoning by, adverse effect of and underdosing of other synthetic narcotics. You have one set of options for fentanyl or fentanyl analogs and another set for tramadol. The codes for “other synthetic narcotics” moved from T40.4X- to T40.49-. Again, you need a 7th character to complete these codes.

The final large update for this chapter adds right, left, bilateral, and unspecified eye options for five subcategories under T86.84- Complications of corneal transplant.

Check the Index

Not all of the ICD-10-CM 2021 code changes involve new, revised, and deleted codes. You may also discover valuable information by reviewing the addenda for tables and indexes.

A good place to start is to check for examples where the ICD-10-CM Index to Diseases and Injuries reroutes one existing code or entry to another. For instance, consider how the 2021 Index has revised the Arthritis, spine entry from “see also Spondylopathy, inflammatory” to “see also Spondylosis.” So instead of looking at a code in the M46.9- Unspecified inflammatory spondylopathy series, the new instruction will take you to the M47.- Spondylosis series.

Another example pertains to the coding of intra-abdominal postprocedural abscesses. When you locate Abscess, intra-abdominal, postprocedural, the 2021 index directs you to T81.43- Infection following a procedure, organ and space surgical site. The 2020 Index pointed to T81.49- Infection following a procedure, other surgical site. This change makes sense because the Tabular List states T81.43- is appropriate for “Intra-abdominal abscess following a procedure.”

CHAPTER 20  External Causes of Morbidity (V00-Y99)

You’ll find the longest list of changes in this chapter of ICD-10-CM 2021. Nearly all of them are in block V00-V09, Pedestrian injured in transport accident. There are now many codes for injuries involving the use of standing electric scooters and any “other standing micro-mobility pedestrian conveyance,” including hoverboards and Segways.

The chapter also includes new codes Y77.11 Contact lens associated with adverse incidents and Y77.19 Other therapeutic (nonsurgical) and rehabilitative ophthalmic devices associated with adverse incidents.

CHAPTER 21  Factors Influencing Health Status and Contact With Health Services (Z00-Z99)

Chapter 21 features new subcategory Z03.82- Encounter for observation for suspected foreign body ruled out with unique codes for encounters where ingestion, aspiration, or insertion of a foreign body has been ruled out.

The other changes to this chapter consist of small corrections and clarifications. For instance, code descriptors in Z68.- Body mass index [BMI] now use brackets rather than parentheses around BMI. The ICD-10-CM Official Guidelines for Coding and Reporting state that brackets in the tabular list “enclose synonyms, alternative wording or explanatory phrases” while parentheses “enclose supplementary words that may be present or absent in the statement of a disease or procedure without affecting the code number to which it is assigned.”

CHAPTER 22  Codes for Special Purposes (U00-U85)

The final chapter in the addenda is also the newest. It includes only U07.0 Vaping-related disorder and U07.1 COVID-19 with their notes, which are effective April 1, 2020. These codes have been covered in AAPC’s Knowledge Center articles “New Diagnosis Code Released for Vaping-Related Disorder” and “Get the Most Out of New ICD-10-CM Addenda and Guideline Updates.”


ICD-10-CM Index to Diseases and Injuries; Tabular List of Diseases and Injuries 2021 Addenda; Tabular List of Diseases and Injuries, 2021:

ICD-10-CM Official Guidelines for Coding and Reporting,

ICD-10-CM Tabular List of Diseases and Injuries April 1, 2020 Addenda,

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