2027 ICD-10-CM Changes: Code Changes & What Practices Need to Know

The fiscal year (FY) 2027 ICD-10-CM update includes 190 new diagnosis codes, 30 deleted codes, and four revised code descriptions. The new code set takes effect October 1, 2026, and applies to healthcare services provided through September 30, 2027.

For medical practices, staying current on these changes is important for maintaining accurate clinical documentation and coding. Using outdated or deleted codes—or documentation that doesn't support the specificity of a new code—can lead to claim corrections, additional administrative work, and potentially avoidable denials.

While coding teams should review the complete FY 2027 ICD-10-CM update and official coding guidelines, here are some of the important changes to know.

2027 ICD-10-CM changes at a glance

What are some of the major ICD-10-CM changes for 2027?

The FY 2027 update introduces new diagnosis codes while deleting or revising others. A common theme across several categories is greater clinical specificity, allowing providers and coding teams to more precisely document and code certain conditions.

Notable areas affected by the FY 2027 changes include:

• Obstetrics and pregnancy
• Cardiovascular conditions
• Toxic exposures
• Other clinical conditions requiring greater diagnostic specificity

Here are a few of the changes medical practices and coding teams should have on their radar.

What obstetrics ICD-10-CM codes are changing in 2027?

Obstetrics is one of the areas receiving significant updates for FY 2027.

The new code set adds greater specificity for ectopic pregnancies, including new codes that distinguish the location of an ectopic pregnancy and whether an intrauterine pregnancy is also present.

Examples include:

• O00.121 — Right interstitial ectopic pregnancy without intrauterine pregnancy
• O00.122 — Left interstitial ectopic pregnancy without intrauterine pregnancy
• O00.129 — Unspecified interstitial ectopic pregnancy without intrauterine pregnancy
• O00.131 — Right interstitial ectopic pregnancy with intrauterine pregnancy
• O00.132 — Left interstitial ectopic pregnancy with intrauterine pregnancy
• O00.139 — Unspecified interstitial ectopic pregnancy with intrauterine pregnancy
• O00.31 — Cesarean scar ectopic pregnancy without intrauterine pregnancy
• O00.32 — Cesarean scar ectopic pregnancy with intrauterine pregnancy

The FY 2027 update also adds new codes related to cervical and cornual ectopic pregnancies, further increasing the specificity available when coding these conditions.

For OB/GYN practices, these changes reinforce the importance of documentation that clearly identifies the type and location of an ectopic pregnancy when known.

What is changing for vanishing twin syndrome?

FY 2027 also introduces a new ICD-10-CM category for continuing pregnancies following vanishing twin syndrome.

The new O31.4- category covers:

Continuing pregnancy after vanishing twin syndrome of one fetus or more

Codes within the category provide additional specificity based on factors such as trimester and fetus.

Providers and coding teams caring for patients with multiple gestations should familiarize themselves with the new category and the documentation needed to support the appropriate code.

What cardiovascular ICD-10-CM codes are changing in 2027?

Cardiovascular coding is another area where the FY 2027 update adds greater specificity.

For example, the existing code for dilated cardiomyopathy is being expanded to distinguish between different forms of the condition.

Dilated cardiomyopathy

Deleted:

• I42.0 — Dilated cardiomyopathy

Added:

• I42.00 — Dilated cardiomyopathy, unspecified
• I42.01 — Familial-genetic dilated cardiomyopathy
• I42.09 — Other dilated cardiomyopathy

There are also changes to the coding of specified cardiac arrhythmias.

Cardiac arrhythmias

Deleted:

• I49.8 — Other specified cardiac arrhythmias

Added:

• I49.81 — Brugada syndrome
• I49.82 — Ventricular bigeminy
• I49.89 — Other specified cardiac arrhythmias, not elsewhere classified

For cardiology practices and other organizations treating patients with these conditions, the changes provide more precise options for documenting and coding a patient's diagnosis.

What toxic exposure codes are changing in 2027?

The FY 2027 update also adds codes for toxic effects associated with certain chemical exposures, including cycloparaffins and other organic solvents.

Examples include:

• T52.821- — Toxic effect of cycloparaffins, accidental (unintentional)
• T52.822- — Toxic effect of cycloparaffins, intentional self-harm
• T52.823- — Toxic effect of cycloparaffins, assault
• T52.824- — Toxic effect of cycloparaffins, undetermined
• T52.891- — Toxic effect of other organic solvents, accidental (unintentional)
• T52.892- — Toxic effect of other organic solvents, intentional self-harm
• T52.893- — Toxic effect of other organic solvents, assault
• T52.894- — Toxic effect of other organic solvents, undetermined

These codes require the appropriate additional character to identify the encounter, such as an initial encounter, subsequent encounter, or sequela. Coding teams should consult the FY 2027 ICD-10-CM Tabular List and official coding guidelines when assigning these codes.

Why do the 2027 ICD-10-CM changes matter for medical practices?

ICD-10-CM updates aren't simply a coding exercise. Diagnosis codes are part of the information practices submit on claims, making accurate coding an important component of an effective revenue cycle.

Issues can arise when:

• A previously used code has been deleted.
• A new, more specific code is available but the documentation doesn't support its use.
• Providers and coding teams aren't aware of changes affecting frequently used codes.
• EHR, practice management, or billing workflows aren't updated to reflect the new code set.
• Internal coding resources or templates continue to reference outdated codes.

Identifying these issues before the October 1 effective date can help practices reduce unnecessary claim corrections and coding-related rework.

How should medical practices prepare for the 2027 ICD-10-CM changes?

Practices don't have to wait until October to prepare. Here are four steps billing leaders, practice administrators, providers, and coding teams can take now.

1. Educate providers and coding teams

Review the changes most relevant to your specialties and patient population.

Providers should understand where greater specificity may require more detailed clinical documentation, while coding teams should know which commonly used codes are being added, revised, or deleted.

2. Review commonly used diagnosis codes

Identify the ICD-10-CM codes your practice uses most frequently and determine whether any are changing for FY 2027.

For specialty practices in particular, reviewing frequently used codes can provide a more focused approach than trying to address every change with the same level of attention.

3. Review coding-related denials

Look at your existing denial trends and identify whether invalid, outdated, or insufficiently specific diagnosis codes are contributing to claim issues.

Understanding where coding-related problems already exist can help identify areas where additional provider education, documentation, or coding review may be valuable.

4. Make sure your systems and workflows are ready

Confirm that your EHR, practice management system, clearinghouse, and other billing technology will support the FY 2027 code set beginning October 1.

Practices should also review internal coding resources, templates, documentation workflows, and training materials that may reference codes being changed or deleted.

Frequently asked questions about the 2027 ICD-10-CM changes

When do the 2027 ICD-10-CM codes take effect?

The FY 2027 ICD-10-CM codes take effect October 1, 2026. They apply to healthcare services provided from October 1, 2026, through September 30, 2027.

How many new ICD-10-CM codes are there for FY 2027?

The FY 2027 ICD-10-CM update includes 190 new diagnosis codes. It also includes 30 deleted codes and four revised code descriptions.

Who maintains ICD-10-CM?

The National Center for Health Statistics (NCHS), part of the Centers for Disease Control and Prevention (CDC), is responsible for ICD-10-CM in the United States.

Where can I find the official 2027 ICD-10-CM codes?

Healthcare organizations and coding professionals can access the official FY 2027 ICD-10-CM code files and supporting resources through the CDC's National Center for Health Statistics and the Centers for Medicare & Medicaid Services (CMS).

Can ICD-10-CM changes affect claim denials?

They can contribute to claim issues. Continuing to submit an invalid or deleted code, selecting an incorrect diagnosis code, or lacking documentation to support the appropriate level of specificity can result in additional claim work and, depending on payer requirements and the circumstances of the claim, denials.

Prepare now for the FY 2027 ICD-10-CM update

The FY 2027 ICD-10-CM changes take effect October 1, 2026, giving practices an opportunity to prepare before the new code set becomes part of their day-to-day billing workflows.

Start by identifying the changes most relevant to your specialty, educating providers and coding teams, reviewing coding-related denial trends, and confirming that your technology and workflows are ready for the new codes.

Most importantly, practices and coding professionals should consult the official FY 2027 ICD-10-CM code set and coding guidelines from the CDC and CMS when making coding decisions.