ICD 9 Codes

Medical Billing Codes – The Foundation of Medical Billing Coding Training

Find out what ICD 9 codes are and their relationship to CPT codes. What is a good ICD-9 codes reference for the medical billing and coding specialist.

ICD 9 medical billing codes are those associated with the diagnosis of a patients condition. Medical coders are very proficient in assigning these medical codes and well trained in their use. Medical billing specialists should be familiar with ICD codes, but do not usually get into them as deep as the coder does – other than a basic introduction in billing medical school training.

ICD stands for International Classification of Diseases. These are a system of diagnosis medical billing codes to classify patient diseases and symptoms. The ICD-9 codes we are discussing are referred to as ICD-9-CM. The “CM” stands for Clinical Modification.

Medicare began requiring the use of ICD 9 diagnosis codes on claims in the 1980’s and was soon followed by commercial insurance providers. These codes are a 5 digit number which has 3 digits followed by a decimal and then a 2 digit number.

ICD-9 Codes Organization
Here’s a categorical listing of IDC 9 codes:

  • 001-139: Infectious and parasitic diseases
  • 140-239: Neoplasms
  • 240-279: Endocrine, nutritional and metabolic diseases, and immunity disorders
  • 280-289: Diseases of the blood and blood-forming organs
  • 290-319: Mental disorders
  • 320-359: Diseases of the nervous system
  • 360-389: Diseases of the sense organs
  • 390-459: Diseases of the circulatory system
  • 460-519: Diseases of the respiratory system
  • 520-579: Diseases of the digestive system
  • 580-629: Diseases of the genitourinary system
  • 630-679: Complications of pregnancy, childbirth, and the puerperium
  • 680-709: Diseases of the skin and subcutaneous tissue
  • 710-739: Diseases of the musculoskeletal system and connective tissue
  • 740-759: Congenital anomalies
  • 760-779: Certain conditions originating in the perinatal period
  • 780-799: Symptoms, signs, and ill-defined conditions
  • 800-999: Injury and poisoning
  • E and V codes: external causes of injury and supplemental classification
  • E800-E999: Supplementary Classification of External Causes of Injury and Poisoning


The ICD 9 codes submitted on an insurance claim are associated with the CPT code to indicate which procedure is associated with the disease or symptom. There may be more than one ICD 9 code associated with each CPT code. The CMS 1500 form can accommodate up to 4 ICD 9 codes in box 21 of the form as referenced by the diagnosis pointer in box 24E.

Free Billing Code Resources
Here’s some links to free references for CPT medical coding and ICD 9 codes from reputable sites. These can be very helpful if you’re just trying to do a quick search for a CPT or ICD-9 code.

Coding References
There are several good online coding tools such as Find-A-Code, Supercoder, CodeitRightonline, and SpeedeCoder to name a few. Most have specialty coding libraries, search tools to answer coding questions, and Medicare compliance features. Most have monthly or annual pricing plans which allows you to select and pay for only the features you need.

For free ICD-9 code look-up, try ICD9Data.com or ICD9.chrisendres.com.

If you prefer traditional paper references, there are also several ICD 9 coding handbooks available with an easy to navigate format that provide clarifications and make it easier to associate the diagnosis code with the description.

I’ve found one of the best paperback coding references for Medical Billing is the latest edition of the CPT-Current Procedural Coding Expert and the ICD-9-CM Expert for Physicians, Volumes 1 & 2-Latest Edition. These are essential references for our medical billing business. They’re available on Amazon, AAPC, AMA, The Coding Institute, and several other online sources – just do a Google or Amazon search.

Most suppliers offer coding references in an easy-to-navigate layout with a logical format. They combine the diagnosis and CPT codes with definitions and illustrations. It has complete code information integrated with intuitive symbols and color coding for all Medicare code edits crucial to reimbursement.

Another excellent reference for medical billing specialists is Understanding Health Insurance.

It’s an excellent source for describing CPT and ICD-9 coding systems, managed care, legal and regulatory issues, reimbursement methodologies, coding for medical necessity, and common health insurance plans. It’s written in an easy to understand style for the complex issues in medical coding and billing and has several practical examples.

ICD-10
ICD-10-CM is a revision to the ICD-9-CM diagnosis codes as required by the Health Insurance Portability Accountability Act (HIPAA). The 7 digit ICD-10 is more specific and allows greater detail in diagnosis than the 5 digit ICD-9 codes. The other difference is ICD-10 uses alphanumeric characters verses numeric for ICD-9. ICD-10-CM will allow not only more codes but also for more specific tracking. This allows providers to better identify certain patients with certain conditions that will benefit from tailored disease management programs such as diabetes or hypertension.

The U.S. Department of Health and Human Services has set a deadline of October 1, 2015 for replacing ICD 9 with ICD-10 codes.

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