The World Health Organization developed a system to attach a code to every diagnosis, symptom or cause of death in the medical arena. They called the system the International Statistical Classification of Diseases, or for short ICD codes. While a CPT code describes a procedure or service provided, ICD medical billing codes are used to explain why this procedure or service was rendered. In this sense, the two codes must be affiliated. One can not charge a CPT code for a cast when the patients complaint (or ICD code) was chest pain. The two are obviously not related and the provider would not get reimbursed for this claim.

The most common guide medical facilities use today is the ICD – 9 codes. The number following the ICD letters indicates the number of complete revisions the codes have gone through. Currently ICD medical billing codes are under going another revision, which will lead us to the ICD – 10 codes guide. This revision is expected to be finished by 2011. The new codes will look very different from the most recent codes. ICD – 9 codes are expressed by three characters to the left of the decimal point and one or two to the right. The new ICD – 10 codes will display two digits, preceded by a letter, to the left of the decimal and one digit to the right. The letter will indicate the category that the disease falls under. For example a ‘Q’ will indicate genetic anomaly. Both the ICD and CPT codes must be submitted with the claim to the insurance company for reimbursement.