Though the U.S. Department of Health and Human Services has recently stated that the deadline for the implementation of ICD-10 may be extended past the original October 1, 2013 date, the International Classification of Diseases is the cornerstone of medical billing and medical coding. The United States healthcare system currently uses the International Classification of Diseases-9th Edition-Clinical Modification (ICD-9-CM) to describe medical conditions and inpatient medical procedures in medical code. Every healthcare provider has a basic knowledge of ICD-9-CM. Professional medical billers and certified medical coders have an in-depth understanding of how this system works, how to apply its principles based on available medical documentation, and how to improve documentation to support the delivery of medically necessary services.

The International Classification of Diseases is a medical coding system devised by the United Nations’ World Health Organization. The United States is the last industrial country to use the 9th version of ICD. All other advanced healthcare economies have already implemented ICD-10. Each country adapts ICD to its particular needs. Due to the Health Insurance Portability and Accountability Act of 1996 (HIPPA), ICD-9-CM is mandated as the only set of codes to be used for reporting medical services in the United States. Barring any changes in mandate, ICD-10 will replace ICD-9-CM in 2013. The two coding systems are similar, and medical billers and medical coders who are fluent in the methodology of ICD-9-CM will be able to adapt to ICD-10, since both systems share a common foundation.

Assigning ICD codes

Every medical code is specifically definition. Diagnosis coding accurately portrays the medical condition that a patient is experiencing. Like all medical codes, ICD diagnostic codes are intended to convey an exact aspect of medical information. ICD diagnostic coding accurately reflects a healthcare providers findings. A healthcare provider’s progress note is composed of four component parts. Firstly, comes the patient’s chief complaint, the reason that initiates the healthcare encounter. Secondly, the provider documents his or observations. This includes a review of the patient’s history, a review of pertinent medical systems, and a physical examination. Following these, the healthcare provider renders an assessment in the form of a diagnosis, and a plan of care.

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In the outpatient setting, a definitive ICD code is assigned only when a definitive diagnosis is reached. In the emergency room, or in an ambulance, a suspected condition is coded to justify the services performed. The same is true in the inpatient setting when conditions may have to be ruled out by performing a variety of tests that turn out to be negative and a conclusive diagnosis is not reached. Different guidelines govern the application of ICD codes depending on the circumstances. In the outpatient setting, a suspected condition is never assigned a code. In these cases, only the symptoms are coded.

For procedure codes included in Volume III of ICD-9-CM and in the International Classification of Diseases-10th Edition- Procedure Coding System (ICD-10-PCS), the procedure performed must be supported by the available documentation in the patient’s medical record.

ICD Reports Data

Diagnostic codes are usually reported in conjunction with procedure codes. The diagnostic codes are used to justify why medical procedures are performed. There are situations when diagnostic codes are reported for purposes other than reimbursement, such as statistical reporting to federal and state health agencies, when submitting reports for drug trials, or for tracking purposes within a healthcare institution to identify patient population needs and trends.

In the outpatient setting, when a healthcare provider suspects a condition, such as a gastrointestinal hemorrhage in a patient, a diagnosis code is not assigned to describe a GI bleed until it is confirmed. The patient will usually undergo a radiological or endoscopic examination to confirm the existence and location of the bleed. At the first encounter, when the patient presents with only a complaint of tarry, black stool, the code 578.1 is used to describe why the patient was examined and the plan of care was devised. The healthcare provider may suspect a hemorrhage in the jejunum, but without direct evidence, he or she assigns the code for blood in the stool and orders a radiological test. The patient is referred to a radiologist who identifies a hemorrhage in the sigmoid colon. Because the radiologist has made a definitive diagnosis, he or she reports the reason for the encounter as being 556.5, left-sided, ulcerative colitis. With the radiologist’s report in hand, the primary care provider follows up with the patient, with the confirmed diagnosis of 556.5, and devises a plan of care. For this follow-up encounter, 556.5 is used to explain the cause for medical intervention.

A dermatologist may excise a suspicious skin lesion from a patient’s ear for a pathologist’s review. The procedure code depends on the definitive diagnosis. The Common Procedural Terminology (CPT code) for the excision of a benign lesion is not the same for the CPT code that denotes the excision of a malignant lesion. If the pathologist reports a diagnosis of basal cell carcinoma (173.21), squamous cell carcinoma (173.22), a melanoma (172.2 ), or another specified malignant neoplasm of the ear (173.29), the description of the procedure performed to remove the lesion is effected. The follow-up visit that describes how the dermatologist devised an appropriate care plan will be reported with the applicable malignant skin cancer code.

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Medical Documentation is Key

The diagnosis code assigned is assigned based on the information available to the coder when the code is assigned. Many dermatologists, for example, bill the procedure code for a skin lesion of uncertain behavior without waiting for a pathology report. If the dermatologist has a strong suspicion of malignancy, he or she may wait until the definitive diagnosis is achieved to support his or her claim of excision of a malignant lesion. As one may assume, the care taken to excise a malignant skin tumor is more extensive than that taken to excise a benign skin fibroma. In the outpatient setting, it is illegal to assign an ICD diagnosis code without definitive documentation that a condition exists. There are many rules to remember.

Primary and Secondary ICD Codes

Some diagnoses are the natural complications of pre-existing conditions. In these cases, the underlying condition is the primary diagnosis. For example, a xanthoma is a benign tumor made up of fatty deposits, usually found in the eyelid. While xanthoma has its own code (277.89), the underlying hyperlipidemia, high cholesterol in layman’s terms, is the root cause. In this case, when a xanthoma is excised, the systemic hyperlipidemia is coded as primary (272.0-272.9) and the xanthoma code is listed as the secondary reason for the procedure. ICD’s structure starts from the basic and leads to the specific. Knowing its nuances will ensure that healthcare claims are submitted appropriately. Coding 277.89 without a primary diagnosis makes no sense from ICD’s perspective.

ICD-9-CM and ICD-10 Structure

The International Classification of Diseases in every version is arranged by type of disease. The first section deals with infectious diseases. The second section deals with neoplasms. Following that is every definable disease listed according to the part of the body that is affected. Codes that refer to bodily injury such as lacerations, crushing, and burns, have their own sections, as do complications following prior surgeries.

With adequate education, professional medical billers and certified medical coders know who to apply ICD diagnosis codes to convey the most accurate information possible based on the patient’s medical record. This grounding in basic understanding of the nuts-and-bolts of coding ensure that the American healthcare system runs efficiently, effectively, and transparently.