ICD-9-CM Coding Overview
Medical billers and medical coders need to have a solid understanding of the International Classification of Diseases-9th Edition-Clinical Modification (ICD-9-CM). ICD-9-CM is divided into three volumes, the first two of which are composed of diagnosis codes, while the third volume contains a list of available procedure codes. Inpatient medical coders and medical billers use the third volume to describe medically necessary services that are provided in the hospital setting. All medical coders and billers rely on Volumes 1 and 2 to support the medical necessity of billed healthcare claims.
The Basics of Diagnosis Coding
Every procedure provided to patients is assigned a code that is linked to a corresponding charge for reimbursement. These procedure codes are also linked to the codes found in ICD-9-CM to report why the procedure was performed. Accurate diagnostic coding is essential to proper reimbursement. Without the correct diagnosis code appended to a service code, payment will be denied as being “not medically necessary.”
A bronchial endoscopy is not medically necessary for a patient who has a blood in his or her urine (599.70), but it is clinically indicated for a patient with chronic obstructive pulmonary disease (496). Since healthcare claims are submitted entirely in universally recognized codes, the proper understanding of the codes’ meaning is paramount to submitting clean claims that will be paid on first submission to private health insurance plans, and to government health insurance programs.
Healthcare providers can assign codes at the time of service, or medical billers and coders can assign codes based on the documentation in the patient’s medical record, which falls within the scope of their professional duties. Different healthcare settings impose different responsibilities on medical billers and coders. In a large medical practice, it may be certified medical coders that are charged with diagnosis code compliance. In a smaller practice of one or two physicians, or in a physical therapy clinic, for instance, the healthcare provider may assign ICD-9-CM codes with input from their office’s professional medical biller.
Healthcare providers do not normally receive any formal training in medical coding or medical billing. For this reason, they rely on trained professionals who specialize in this administrative discipline for guidance in complying with the standards set forth in ICD-9-CM. Professional medical billers and certified medical coders are individuals who have usually completed formal programs of study that enable them to understand the methodologies and protocols established by ICD-9-CM and professional associations to report a healthcare provider’s findings as documented in the patient’s medical record.
Organization of ICD-9-CM
ICD-9-CM is updated annually as new codes are added to keep current with the current language of medicine, old codes are eliminated that are found to no longer accurately describe current understanding of conditions, and code definitions are modified to provide a more accurate picture of a patient’s state of health.
Volume 1 of ICD-9-CM is an alphabetical listing of the conditions contained within the code manual. Medical coders and medical billers use this volume to locate where a specific condition is located in the tabular index. Volume 1 offers an indication of what code may be appropriate to describe a specific medical condition, but no professional medical biller or certified medical coder relies on Volume 1 of ICD-9-CM to report medical conditions. Volume 1 does not include the granularity of data that is essential for accurate diagnostic coding. For that, medical billers and medical coders cross reference what they find in Volume 1 with the tabular listings in Volume 2.
Volume 2 is the heart of the ICD-9-CM, and it is the volume that is referred to most regularly. Volume 2 contains the complete list of available codes from 001.0 to 999.9. These codes are not arranged randomly, instead, they are divided according to body systems and related conditions. There is a section on infectious and parasitic diseases, a section on diseases of the circulatory system, and a section that covers diseases of the skin and subcutaneous tissue, among others. When a definitive diagnosis cannot be reached, ICD-9-CM contains a set of codes to describe signs and symptoms. A fully-trained professional medical biller or medical coder can recognize what part of the body is affected by what numbers a diagnosis code starts with. For instance, a code falling between 910 and 919 represents a superficial injury.
Familiarity with ICD-9-CM codes increases efficiency when healthcare claims are assembled. Professional medical billers and coders can recognize when a code may be incorrectly assigned. By investigating the patient’s medical record, or querying the healthcare provider, coders and billers can correct a claim before it is submitted for payment. This reduces unnecessary denials of coverage and eliminates the need to appeal coverage for services deemed not medically necessary.
Components of an ICD-9-CM Code
Professional medical billers and certified medical coders recognize that ICD-9-CM codes are composed of between three and five digits. The first three digits identify the primary condition. These are followed by a decimal point, when applicable, and then another one to two numbers to provide more specificity. For example, the code 402 describes hypertensive heart disease, but this is not a billable code since it is incomplete. It requires more digits, meaning that more information is required to make this code understandable. 402.0 is malignant hypertensive heart disease, but even that extra digit is not enough to make a billable code. ICD-9-CM requires the utmost available specificity to make a diagnosis code understandable. In the case of 402.0, that extra digit can be a 1 or a 2, depending on the patient’s condition, but it cannot be any other number. A professionally-trained medical coder or a certified medical biller knows when three digits are appropriate, or four, or five, and what those numbers should be.
ICD-9-CM codes are not only composed of numbers. Codes that start with the letter V are used to describe factors that influence health status to justify medical encounters. For instance, V10.4 is used to report that a patient has a history of stomach cancer without currently showing any signs or symptoms . Codes that start with E provide supplementary information of how injuries occurred. V-codes are rarely used as the primary diagnosis code on healthcare claims. E-codes never are.
While this article does not discuss the procedural codes contained in Volume 3 of ICD-9-CM, professional medical billers and certified professional coders are proficient in their use if the occasion calls for them. Volumes 1 and 2 are the pillars on which the medical reimbursement system stands in the United States. Every healthcare claim, whether it originates from inpatient medical billing, outpatient medical billing, skilled nursing facility (SNF) billing, or ambulatory surgical center (ASC) billing relies on ICD-9-CM to report medically necessary services to third-party payers.
Professional medical billers and professional medical coders are trained to understand the nuances of ICD-9-CM coding through the application of their background in medical terminology, anatomy and physiology, and the current state of medical practice. They work closely with healthcare providers to submit accurate insurance claims to private medical insurers and to government healthcare programs. Through the accurate application of ICD-9-CM codes, medical billers and medical coders keep their employers compliant with existing regulations and policies in an ever-changing regulatory environment designed to discourage healthcare fraud and abuse.