How to Look Up an ICD Code for Your Diagnosis

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International Classification of Diseases (ICD) codes are found on patient paperwork, including hospital records, medical charts, visit summaries, and bills. These codes ensure that you get proper treatment and are charged appropriately for any medical services you receive.

The 10th version of the code, in use since 2015, is called the ICD-10 and contains more than 70,000 disease codes. The ICD is maintained by the World Health Organization (WHO) and distributed in countries across the globe.

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In the United States, ICD codes are overseen by the Centers for Medicare and Medicaid Services (CMS) and the National Center for Health Statistics (NCHS). 

The ICD receives annual updates in between revisions, which is sometimes reflected in the code title. For example, the 2020 updated version is the ICD-10-CM. The ICD-11 was approved by the WHO in 2019 and goes into effect in 2022.

How ICD Codes Are Used

ICD codes are used in billing, treatments, and statistics collection. Having the right code is important for being reimbursed for medical expenses and ensuring the standardized treatment for your medical issue is delivered.

Insurance Reimbursement

When your healthcare provider submits a bill to insurance for reimbursement, each service is described by a common procedural technology (CPT) code, which is matched to an ICD code. If the two codes don't align correctly with each other, payment may be rejected.

In other words, if the service isn't one that would be typically provided for someone with that diagnosis, insurance will not pay. For example, your healthcare provider could not typically submit a bill for an X-ray if you come in complaining of a rash; imaging is not indicated for that concern.

Disease Management

An ICD code is assigned for every disease, and if you have a chronic illness, such as diabetes or heart disease, your ICD code will typically follow your medical records.

In a hospital setting, this can be lifesaving in that it can prevent you from getting treatment that is contraindicated for your chronic disease. On the other hand, for patients with chronic conditions who come to the hospital for an unrelated acute issue, this can cause frustration.

Whenever you meet a new healthcare provider , they often ask a lot of questions about the chronic illness first instead of focusing on your reason for being in the hospital. While a condition may seem unrelated to you, there may be a connection.

Still, this sometimes results in a provider ordering unnecessary testing and treatments that are indicated for the chronic condition, rather than focusing on the acute concern that brought you in.

Other Uses

ICD codes are used globally to track health statistics and causes of death. This is helpful for gathering data on chronic illnesses as well as new ones. For example, a new code was added to the ICD-10 in 2020 to track vaping-related illnesses.

ICD codes are also used in clinical trials to recruit and track subjects and are sometimes, though not always, included on death certificates.

ICD Code Updates

The 2015 revision to the ICD involved a number of changes to the system. As a result, ICD-10 codes are approached differently from their ICD-9 counterparts.

ICD-9 Codes

While phased out in 2015, you will still see ICD-9 codes on older documents. Most ICD-9 codes are three digits to the left of a decimal point and one or two digits to the right of one. For example:

  • 250.0 is diabetes with no complications.
  • 530.81 is gastroesophageal reflux disease (GERD).
  • 079.99 is a virus.

Some ICD-9 codes have "V" or "E" in front of them. A "V" code is used for health services (usually preventive) that don't require a diagnosis. An "E" code describes an environmental cause of a health problem, such as an injury or poisoning.

ICD-10 Codes

The ICD-10 update completely overhauled the coding system. The new codes are broken down into chapters and subchapters and include a letter plus two digits to the left of the decimal point, then one digit to the right.

The new system allows for a more specific diagnosis. For example:

  • E10.9 is type 1 diabetes and E11.9 is type 2 diabetes.
  • K21.9 is GERD.
  • B97.89 is a virus as a cause of disease classified elsewhere.

The letters group diseases together and describes a specific condition, organ system, or characteristic of a condition. This may cause initial confusion because "E" no longer stands for an environmental cause, but rather endocrine disorders.

ICD-10 Diagnostic Codes From A to Z

  • A: Infectious and parasitic diseases
  • B: Infectious and parasitic diseases
  • C: Cancer
  • D: Neoplasms, blood, and blood-forming organs
  • E: Endocrine, nutritional, or metabolic
  • F: Mental and behavioral disorders
  • G: Nervous system
  • H: Eyes, ears, nose, and throat
  • I: Circulatory system
  • J: Respiratory system
  • K: Digestive system
  • L: Skin
  • M: Musculoskeletal system
  • N: Genitourinary system
  • O: Pregnancy and childbirth
  • P: Perinatal conditions
  • Q: Congenital and chromosomal abnormalities
  • R: Abnormal clinical and lab findings
  • S: Injury, poisoning, and other external causes
  • T: Injury, poisoning, and other external causes
  • U: Used for emergency designation
  • V: External causes of morbidity
  • W: External causes of morbidity
  • X: External causes of morbidity
  • Y: External causes of morbidity
  • Z: Factors influencing health status and contact with health services

ICD-11 Codes

In 2022, the ICD codes will change again with the addition of two numbers—one that precedes the letter and one that comes at the end. For example, X98.6 (ICD-10 code) will become 0X98.60. The updated code also does not use letters "I" or "O" to avoid confusion with 1 and 0.

Where to Find ICD Codes

When you leave a healthcare provider's appointment, therapy appointment, or hospital, you are given a visit summary that should include different number codes. The ICD codes are listed under "diagnosis" or "Dx," while other codes are typically CPT codes for services rendered.

When you receive an explanation of benefits (EOB) from your insurance company, Medicare, or another payer, it also contains ICD codes. If a claim is not being paid, it may be because the ICD code does not align with the CPT code. If this occurs, speak with your healthcare provider.

If you need to look up the ICD code for a particular diagnosis or confirm what an ICD code stands for, visit the Centers for Disease Control and Prevention (CDC)'s website to use their searchable database of the current ICD-10 codes.

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7 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Centers for Disease Control and Prevention. International Classification of Diseases, tenth revision, clinical modification (ICD-10-CM).

  2. World Health Organization. WHO releases new International Classification of Diseases (ICD 11). June 18, 2018.

  3. Centers for Disease Control and Prevention. New ICD-10-CM code for vaping-related disorder to be implemented April 1, 2020.

  4. Centers for Disease Control and Prevention: National Center for Health Statistics. Classification of diseases, functioning, and disability.

  5. Cartwright DJ. ICD-9-CM to ICD-10-CM codes: What? why? how? Adv Wound Care (New Rochelle). 2013;2(10):588–592. doi:10.1089/wound.2013.0478

  6. World Health Organization. ICD-11 reference guide.

  7. Centers for Disease Control and Prevention. ICD-10-CM.