What Is ICD-10?

Whether you are a new healthcare professional just learning the ropes or a hospital administrator managing billing systems, one thing is certain - you might have heard of ICD-10. But do you really know how deeply it impacts everyday healthcare?

ICD-10 codes are the silent engine powering everything behind the scenes, from diagnosing a common cold to processing a complex surgery claim. ICD-10 is not only a list of codes, but a global language that connects clinical care, hospital records, and insurer systems. Therefore, it is essential to understand how it works to improve the accuracy and compliance. This blog will help you in a better understanding of the ICD-10 codes.

ICD-9 vs. ICD-10

ICD-10 is the updated version of the International Classification of Diseases, which replaced the older ICD-9 system. One of the most significant differences is the number of codes available. ICD-9 had approximately 13,000 codes, whereas ICD-10 has over 68,000, allowing for much more detailed and specific diagnosis and procedure coding.

ICD-10 codes also have up to 7 characters compared to the maximum of 5 characters in ICD-9, which helps healthcare providers describe the exact location, cause, and severity of a condition more accurately. This enhanced level of detail supports improved treatment, billing accuracy, and effective health data tracking. ICD-9 was limited in keeping up with medical advancements, which is why the transition to ICD-10 became essential.

What is ICD-10?

The International Classification of Diseases, Tenth Revision (ICD-10) is a standardized coding system developed by the World Health Organization to classify diseases, conditions, symptoms, and procedures. It enables hospitals and other healthcare providers worldwide to communicate using a universal medical language. All this ensures consistency in diagnosis documentation and healthcare delivery.

Structure of ICD-10 Codes

Each ICD-10 code can be up to seven characters long and follows a specific format:

• The first three characters identify the general category of the condition.
• A decimal point follows after the third character.
• The next three or four characters provide specific details such as location, cause, and severity of the condition.

Importance of ICD-10 Codes

ICD-10 codes are essential for insurance claims and treatment validation. They are vital for processing insurance claims, as they ensure that the diagnosis recorded supports the treatment or procedure billed. For example, if a provider codes an ankle sprain (S99.91) but submits a claim for a hand X-ray, the insurer may reject the claim due to a mismatch. Such errors can result in delayed payments, claim denials, or unexpected out-of-pocket expenses for patients.

How to Check ICD-10 Codes

The healthcare providers or coders can check ICD-10 codes easily using the following methods:

• Use the CDC’s ICD-10 Lookup Tool: Visit the Centres for Disease Control and Prevention (CDC) website to search for or verify ICD-10 codes through their free searchable database.
• Use of EHR Systems: Most EHR platforms have built-in ICD-10 lookup tools that auto-suggest diagnosis codes based on entered clinical notes or selected conditions.
• Medical Coding Software & Tools: Healthcare providers and coders can access advanced platforms, such as 3M CodeFinder, Optum EncoderPro, TruCode, or Find-A-Code, for quick and accurate ICD-10 code lookups and compliance checks.
• Reference to ICD-10 Codebooks: Many healthcare professionals still refer to printed ICD-10-CM codebooks, published by the AMA or AAPC, for offline access and to learn detailed coding guidelines.
• Official CMS & WHO Websites: Providers can access updated code lists, downloads, and mapping tools on the CMS website or check international coding details on the WHO portal.
• Consultation with Certified Medical Coders: Healthcare providers may consult Certified Professional Medical Coders for support in assigning accurate ICD-10 codes, especially for complex or unusual diagnoses.

ICD-10-CM Updates for 2025

CMS has announced the ICD-10-CM code updates for Fiscal Year 2025, which will take effect on October 1, 2024. These update comprises 252 new diagnosis codes, 36 revisions, and 13 deletions. Such as:

• Lymphoma in Remission

A total of 63 new codes have been added to the C81-C96 range to indicate whether a patient's lymphoma is active or in remission. Such an addition helps improve disease monitoring, evaluate treatment results, and plan future patient care.

• Presymptomatic Type 1 Diabetes

The new codes in the E10.A1–E10.A9 range identify presymptomatic Type 1 diabetes, enabling early diagnosis before symptoms develop. This helps providers initiate preventive care and monitor patients at risk.

• Personal History of Polyps

The four new codes within Z86.018–Z86.01A have been added to distinguish between non-neoplastic and neoplastic colon polyps. This supports better identification of patients at risk for colorectal cancer and enhances screening protocols.

• Fanconi Anemia

A specific code has been introduced for Fanconi anaemia, i.e., D61.03, which is meant for a rare genetic disorder that impacts the bone marrow. It is now classified as a complication and comorbidity to support more accurate patient categorization.

• Obesity Classifications

The updated codes in the E66.811 to E66.89 range help classify obesity based on its severity. Class 1 includes people with a BMI between 30 and 34.9, Class 2 covers a BMI from 35 to 39.9, and Class 3 includes those with a BMI of 40 or higher. These changes make it easier for healthcare providers to assess the severity of a person's obesity and to create more personalised treatment plans based on that information.

• Eating Disorders

The codes under F50.010–F50.029 now differentiate between restricting and binge-purge subtypes of anorexia nervosa. They also include severity levels based on BMI, allowing for more precise diagnosis and care strategies.

• Pulmonary Embolism

The four new codes, such as I26.03–I26.04 and I26.95–I26.96, distinguish fat and cement pulmonary embolisms. These codes help accurately capture complications from trauma, liposuction, orthopaedic procedures, and vertebroplasty.

• Nasal Valve Collapse (NVC)

The seven new codes in the J34.820–J34.827 range identify internal or external nasal valve collapse, and specify whether the condition is static or dynamic. This improved classification facilitates more accurate diagnosis of nasal airway obstruction.

• Congenital Heart Conditions

The new codes in the Q23.81–Q23.88 range document congenital disabilities such as a bicuspid aortic valve. These updates facilitate the tracking of disease progression and include coding notes to document any related acquired valve disorders.

• Immune Checkpoint Inhibitor Reactions

The eighteen new codes under T45.X5A-T45.X5S have been added to capture poisoning, adverse effects, and underdosing of immune checkpoint inhibitors. These codes support the safe monitoring of cancer therapies that affect multiple organ systems.

Future Outlook

The WHO has introduced ICD-11 as the next version of the ICD-10. This updated system is more adaptable and designed with digital healthcare in mind. It works more efficiently with electronic health records to make the clinical documentation easier for providers. ICD-11 also includes new classifications that reflect advancements in medical science and modern healthcare needs.

Although ICD-11 is available for use, many countries (including the United States) are still evaluating how and when to implement it. Healthcare providers should begin preparing now. For example - familiarizing the in-house team with the new coding system, updating the software, and training staff to handle upcoming changes. These proactive steps will make the future transition to ICD-11 more manageable.

Conclusion

ICD-10 has transformed the way the healthcare industry codes and communicates medical information. It has improved diagnostic precision, enhanced monitoring of diseases worldwide, and made medical billing more transparent. But managing ICD-10 coding in-house can be a time-consuming, complicated, and error-prone process for a busy hospital, clinic, or healthcare provider already operating at capacity.

To meet these complexities, most healthcare organizations today are opting for the outsourcing of medical billing and coding services to specialized partners. 24/7 Medical Billing Services ensures access to certified coders, reduces claim denials, and allows providers to enhance healthcare reimbursement. As the industry looks ahead to the adoption of ICD-11, staying updated and strategically supported by the outsourcing experts can help providers remain compliant, efficient, and financially strong.

FAQs

Q1. Can ICD-10 codes be used to track disease outbreaks?

Hospitals use ICD-10 data to monitor and respond to disease trends and epidemics.

Q2. Are ICD-10 codes different from CPT codes?

ICD-10 codes describe diagnoses, while CPT codes describe procedures and services.

Q3. Are there training programs for ICD-10 coding?

Many accredited institutions and online platforms offer training and certification for medical coders.

Q4. Do EHR systems automatically assign ICD-10 codes?

Some Electronic Health Record systems suggest codes, but final responsibility lies with the provider or coder.

Q5. Will ICD-11 replace ICD-10 soon?

The WHO has released the ICD-11, but widespread adoption is expected to occur gradually over the coming years.