Sometimes, the ICD-10-CM guidelines demand that a particular medical condition be reported using multiple diagnosis codes. This practice is known as “mandatory multiple coding,” “dual classification,” “dual coding,” or “mandatory dual coding.” A specific instance of this mandatory dual coding is included in the “etiology/manifestation conventions,” which involves reporting both the disease (the underlying problem or ’cause’) and one of its manifestations (the secondary condition or ‘effect’ caused by the problem).
Etiology and Manifestation
Etiology codes refer to the underlying diseases, and it should always be listed before the code for any related manifestation. When considering a diagnosis as an etiology code, ensure that a valid manifestation code is assigned immediately after the etiology code.
The manifestation code describes a condition caused by an underlying disease but cannot be used as the primary diagnosis. It is always used with an underlying condition code and never as a principal diagnosis. The code title often includes “in diseases classified elsewhere” to indicate its role in the etiology/manifestation convention.
A prime example of mandatory dual coding is secondary sideroblastic anemia (D64.2). It cannot be coded alone because D64.2 is a manifestation code that is always caused by an underlying problem. For instance, Osteonecrosis in diseases classified elsewhere, left upper arm (M90.522) can be one of the causes of D64.2. If you intend to use D64.2 for your M1021/3 list, you must list it beneath an etiology code, where M90.522 will be listed above D64.2 on the list.
An example of mandatory dual coding is diabetic nephropathy (E11.21). Diabetic nephropathy is a manifestation of diabetes and cannot be coded alone. It must be coded along with the underlying diabetes code (E11.-) to indicate the relationship between the two conditions. For instance, if a patient has type 2 diabetes mellitus (E11.9) and is also diagnosed with diabetic nephropathy, the dual coding would involve listing E11.9 as the primary diagnosis code and E11.21 as a secondary code to specify the manifestation of nephropathy related to diabetes. This ensures accurate representation of the underlying condition and its associated manifestation for proper documentation and reporting.
Proper Code Sequencing
The way diagnosis codes are positioned can have a significant impact on the clinical grouping of a claim and may even trigger adjustments in reimbursement levels. Therefore, it is crucial to understand the complexities of diagnosis sequencing, including identifying primary and secondary diagnoses. It is important to note that a diagnosis documented as the primary reason for home health during the face-to-face encounter may end up being classified as the first secondary diagnosis due to rules such as manifestation, etiology codes, or “code first” coding instructions.
There are manifestation codes that do not have “in diseases classified elsewhere” in the title. For such codes, there is a “use additional code” note at the etiology code and a “code first” note at the manifestation code, and thus the rules for sequencing apply.
When assigning a primary diagnosis, one must take into account the primary service provided and the discipline with the highest frequency. Because of these various factors, there may be variations in the sequencing of diagnoses.
Why Coding Proficiency Matters
Medical coding is a complex function that demands a high level of analysis and attention to detail. It is a crucial component of healthcare administration, as it ensures that patients receive the right healthcare services and that providers are reimbursed appropriately for their services. The knowledge and expertise of coders are essential in preventing claims denial and optimizing reimbursements. As such, it is crucial that home health agencies should work with highly skilled coders to ensure patient-centric care and the financial viability of the business.
