How to Look up the ICD Code for Your Diagnosis

ICD Codes, International Classification of Diseases codes, are found on patient paperwork, including hospital records, physician records, and death certificates.

ICD codes could be important to a patient for a variety of reasons:

When your doctor submits her bill to insurance for reimbursement, each service described by a CPT code must be matched to an ICD code. If those 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, the doctor won't get paid. For example, the doctor could not typically submit a bill for an x-ray if the patient's complaint was a rash.
If you have a chronic disease, once an ICD code has been assigned, it may affect the treatment you receive if your provider looks at the code. That would most likely happen in a hospital where a doctor who is not the one who usually treats you (a hospitalist), or with a doctor who reviews your records before he sees you. That ICD determination can be a good thing or a bad thing. It may mean you won't receive a certain medication because your disease code means it is contraindicated. Or, it may mean you do receive a treatment that isn't necessarily useful, but the hospital will be able to bill for it.

If you have a rare disease, then your ICD code may be used to admit you to a clinical trial.
An ICD code may appear on a death certificate. ICD codes are used to track causes of death, but that coding more likely takes place after the death and is not always recorded on the death certificate.

What Does an ICD-9 Code Look Like?

ICD-9 codes and ICD-10 codes actually look quite different from each other. ICD-9 codes, which you'll find on current paperwork, were phased out by October 1, 2015. However, you'll still find ICD-9 codes on paperwork until then, and you'll see them recorded for deaths.

Most ICD-9 codes are comprised of three characters to the left of a decimal point and one or two digits to the right of the decimal point. Examples:

250.0 means diabetes with no complications
530.81 means gastro reflux disease (GERD)
079.99 means a virus

Some ICD-9 codes have V or E in front of them. A V code designates a patient who is accessing the healthcare system for some reason that won't require a diagnosis, usually a preventive reason. Examples:

V70.0, the code for a general health check-up
V58.66 specifies that a patient is a long-term aspirin user
V76.12 is coded for a healthy person who gets a mammogram
V04.81 is the most common code for a flu shot

An ICD-9 code with an E specifies that the health problem is the result of an environmental factor such as an injury, accident, a poisoning or others. A car accident code will be preceded by an E, as will a code for a victim of a plane crash or a snake bite or any other health problem caused by outside force. Medical errors are reported using some of these ICD E codes.

What Does an ICD-10 Code Look Like?

Old ICD-9 codes are being replaced by ICD-10 codes. There are a number of changes to the system, and that includes the codes themselves.

ICD-10 codes are approached differently and are quite different from their ICD-9 counterparts. These codes are broken down into chapters and subchapters. They are comprised of a letter plus two digits to the left of the decimal point, then one digit to the right. The letters group diseases. All codes preceded by a C indicate a malignancy (cancer), codes preceded by a K indicate gastrointestinal problems, and so forth.

Examples are:

A02.0 indicates a salmonella infection
I21.X refers to myocardial infarction
M16.1 is used for arthritis in the hip
Q codes represent genetic abnormalities, like Q35 for a baby born with a cleft palate
U codes are for new problems that develop over time. Any of the antibiotic-resistant "superbugs" that develop over time will fall into the U category.

Patient Paperwork - Where to Find ICD Codes

As we leave a doctor's appointment, check out of the hospital, or any other medical facility, we are handed paperwork that, to the professionals, is a numeric summary of the services they provided to us. The codes with decimal points in them are the ICD codes. They may be designated as "Diagnosis" or "Dx" (shorthand for diagnosis.)There are other codes on that paperwork, too. Some may be CPT codes, which may have numbers or letters and won't have a decimal point.
When we receive an EOB, Explanation of Benefits, from our payer (insurance, Medicare or others), then it will show how much of each service was paid for on our behalf. Each ICD code will be aligned with its CPT code. Both must be listed in order for the doctor to be paid.

How to Match ICD Codes to the Diagnosis They Represent

If you have paperwork that has an ICD code on it, and you want to figure out what that code represents, you can do so in a number of ways:

Find lists of ICD codes online:

Until ICD-9 codes are phased out, you may need to match both codes. Doctors adopted the new sets at different times.

Find a master list of ICD-9 codes at the CDC website.
Search for individual ICD-9 codes in this online searchable database.
The master list of ICD-10 codes can be found on the WHO website. It is searchable. Note that the list may not always be totally current. If you encounter a code that is not on this WHO ICD-10 code list, then you'll want to poke around the WHO website to find a more updated list.
Find another searchable list of ICD-10 codes.
If you are unable to find the information you need about your diagnosis and its ICD code, contact your doctor's office and ask them to help you.