Multiple coding for a single condition

In addition to the etiology/manifestation convention that requires two codes to fully describe a single condition that affects multiple body systems, there are other single conditions that also require more than one code. “Use additional code” notes are found in the Tabular List at codes that are not part of an etiology/manifestation pair where a secondary code is useful to fully describe a condition.

The sequencing rule is the same as the etiology/manifestation pair, “use additional code” indicates that a secondary code should be added, if known.

For example, for bacterial infections that are not included in chapter 1, a secondary code from category B95, Streptococcus, Staphylococcus, and Enterococcus, as the cause of diseases classified elsewhere, or B96, Other bacterial agents as the cause of diseases classified elsewhere, may be required to identify the bacterial organism causing the infection.

A “use additional code” note will normally be found at the infectious disease code, indicating a need for the organism code to be added as a secondary code. “Code first” notes are also under certain codes that are not specifically manifestation codes but may be due to an underlying cause.

When there is a “code first” note and an underlying condition is present, the underlying condition should be sequenced first, if known. “Code, if applicable, any causal condition first” notes indicate that this code may be assigned as a principal diagnosis when the causal condition is unknown or not applicable.

If a causal condition is known, then the code for that condition should be sequenced as the principal or first-listed diagnosis. Multiple codes may be needed for sequela, complication codes and obstetric codes to more fully describe a condition. See the specific guidelines for these conditions for further instruction.