Lesson

ICD-10-CM contains 21 chapters. Chapter 1 of ICD-10-CM represents certain infectious and parasitic diseases. Within each chapter, subchapters are arranged in what are referred to as blocks. You will notice that in each chapter in the Tabular List of ICD-10-CM, you are provided with a list of the blocks for that particular chapter. This gives you a good overview of the contents for each chapter. In addition to reviewing the blocks, you will want to ensure that you always review the instruction notes found at the beginning of each chapter. Here is an example of the instruction notes found at the beginning of Chapter 1 in ICD-10-CM.

Chapter 1 Certain infectious and parasitic diseases (A00-B99) Includes: diseases generally recognized as communicable or transmissible Use additional code to identify resistance to antimicrobial drugs (Z16-)

Excludes 1: certain localized infections—see body system-related chapters infectious and parasitic diseases complicating pregnancy, childbirth and the puerperium (O98.-) influenza and other acute respiratory infections (J00-J22)

Excludes 2: carrier or suspected carrier of infectious disease (Z22.-) infectious and parasitic diseases specific to the perinatal period (P35-P39)

These notes provide important guidelines that are critical to complete and accurate coding. When found at the beginning of the chapter, these instruction notes apply to the entire chapter. That is why it is vital to always review the instruction notes at the beginning of the chapter to ensure that you do not overlook these guidelines.

Combination codes and mandatory multiple coding are a couple of the coding concepts introduced this week. Combination coding is where a single code represents both the condition and the causative organism. You will see good examples of this when coding infectious and parasitic diseases. Here is an example: Conjunctivitis due to adenovirus (B30.1). A single code captures the condition (conjunctivitis), as well as the causative organisms (adenovirus). Mandatory multiple coding, on the other hand, is when you are required to use more than one code to adequately describe both the etiology and manifestation of a condition. In this scenario, the underlying condition must always be sequenced first followed by an additional code for the manifestation. In the Alphabetic Index, both conditions are listed together, with the etiology code listed first followed by an additional code in brackets. The code in brackets must always to be sequenced second. An example of this is Alzheimer’s disease with dementia G30.9 [F02.80]. G30.9 represents the Alzheimer's disease (which is the underlying condition), and F02.80 represents the dementia (which is the manifestation, a result of the Alzheimer’s disease). There is also the concept of discretionary multiple coding. In this scenario, the instruction note would read, “code, if applicable, any causal condition first.” You would only assign the additional code if the causal condition is documented.

Sepsis is a condition that is frequently seen in hospital settings. There are varying degrees of sepsis in terms of severity, each indicated by a different code. When sepsis is associated with acute organ dysfunction, you will need to assign a code for the underlying infection, as well as an additional code for the specific acute organ dysfunction such as acute kidney failure. HIV is also included in this chapter. Once again, you will need to review the chapter-specific coding guidelines for HIV coding. There are some very specific guidelines relevant to whether the condition is asymptomatic versus symptomatic, suspected versus confirmed, and so on.

Chapter 2 of ICD-10-CM represents neoplasms. When coding neoplastic diseases, you will need to make use of the Neoplasm Table found in the Alphabetic Index of ICD-10-CM. The Neoplasm Table lists neoplasm by anatomical site. Once you have located the correct site, use the table to select the appropriate code based on whether the neoplasm is malignant, benign, uncertain, or unspecified behavior. Malignant neoplasm codes are further divided based on primary site, secondary site, or in situ.  The location at which the cancer started or originated is known as the primary site. A secondary site is a place to which the cancer has metastasized or spread. A neoplasm is in situ if it is confined to its point of origin and has yet to invade surrounding tissue. A benign neoplasm is one that is not malignant in nature and so will not spread. A neoplasm is of uncertain behavior when the pathologist cannot ascertain its type. When there is no additional or supporting information, use the unspecified nature. As a general rule, you would always start with the Neoplasm Table unless a specific morphology is stated, such as “sarcoma.” When the morphology is stated, you would refer to that specific term in the Alphabetic Index first rather than going directly to the Neoplasm Table. Using sarcoma as an example, when you reference sarcoma in the Alphabetic Index, you will find “ Sarcoma (of) — see also Neoplasm, connective tissue, malignant.” This provides guidance on the correct use of the Neoplasm Table and the appropriate column to select from once there. In this scenario, per the instruction found in the Alphabetic Index for sarcoma, you would first locate connective tissue in the Neoplasm Table, then select the appropriate code from the column for malignant.

Metastasis is the spreading of the malignancy from its original site. Sometimes the terms metastasis or metastatic are used a bit ambiguously. When the health record states metastatic to, such as a patient with lung cancer that has metastasized to the liver, this means that the lung would be the point of origin (primary malignancy) which has spread to the liver (secondary site). They may also state metastatic liver cancer from the lung. Again, this tells you that the lung is the primary (from) and the liver is the secondary (to). At times, you will find the documentation unclear, such as “patient with metastatic lung cancer.” What does that statement actually mean? Is it telling you that the lung is the point of origin, or that the lung is where the cancer has spread to? In this scenario, you will need to query the physician. There are times when the primary site is unknown. For this situation, you would assign C80.1 for malignant (primary) neoplasm, unspecified. Similarly, if the doctors know that the cancer has spread but have not yet identified the secondary site, it would be appropriate to use C79.9 for secondary malignant neoplasm of unspecified site. This code includes metastatic cancer not otherwise specified.

Chapter 3 of ICD-10-CM covers diseases of the blood and blood-forming organs and certain disorders involving the immune mechanism. You will find that there aren’t any chapter-specific guidelines for this chapter. One of the most common blood-related diseases is anemia. There are several different types of anemia and there is usually a specific cause for anemia. As such, the physician must include specific information in the documentation in order for you to code to the highest level of specificity possible. When the documentation indicates a particular reason, such as acute blood-loss anemia or an iron or other nutritional deficiency, then a specific code is needed to indicate that reason. Occasionally, two codes may be needed to explain the manifestation and the disease causing it. It is important to pay close attention to the instructional notes such as “code first” and “use additional code” to ensure that you are coding accurately and completely.

Although there aren’t any specific guidelines for Chapter 3 in the ICD-10-CM Official Guidelines for Coding and Reporting, Chapter 2 provides guidelines for coding anemia associated with malignancies and for anemia associated with chemotherapy, immunotherapy, and radiation therapy.

Chapter 4 of ICD-10-CM represents endocrine, nutritional, and metabolic diseases. The most frequently used codes in this section are for diabetes mellitus. This is another section where you will see extensive use of combination codes to identify the type of diabetes mellitus, the body system affected, and the complications affecting that body system. Diabetes is classified as type 1 or type 2. If the type of diabetes is not documented in the health record, the default is type 2. There are also categories for secondary diabetes, such as diabetes that is due to another underlying cause or an adverse effect of a drug. It is not uncommon for diabetic patients to have more than one type of complication from diabetes, such as neuropathy, retinopathy, skin ulcers, etc. The coder must assign as many codes as necessary to fully capture all associated conditions that the patient has. You might also see documentation of diabetes that is stated as “inadequately controlled,” “poorly controlled,” or “out of control.” ICD-10-CM classifies this by reporting the diabetes, by type, with hyperglycemia.

This chapter also includes conditions such as malnutrition, obesity, and dehydration. These are fairly common conditions found in inpatient records. When coding obesity, you must also use an additional code to capture the patient’s body mass index, or BMI. Often, the documentation to support the correct BMI code is found in documentation from other clinical staff such as the nutritionist or nurse. Per the ICD-10-CM Official Guidelines for Coding and Reporting (1.B.14), “For the Body Mass Index (BMI), depth of non-pressure chronic ulcers and pressure ulcer stage codes, code assignment may be based on medical record documentation from clinicians who are not the patient’s provider (i.e., physician or other qualified healthcare practitioner legally accountable for establishing the patient’s diagnosis), since this information is typically documented by other clinicians involved in the care of the patient (e.g., a dietitian often documents the BMI and nurses often documents the pressure ulcer stages). However, the associated diagnosis (such as overweight, obesity, or pressure ulcer) must be documented by the patient’s provider.”