Default Causal and effect relationship for combination codes

Understanding when to use combination codes in ICD-10 CM can be tricky, even when you have both diagnoses. Let's break it down together.

Let’s start with Example,

1. Patient has hypertension and CKD.

2. Patient has Anxiety and depression.

The answer for first example is I12.9, N18.9. Here in the example, physician is not giving the linkage, but we will presume the linkage between them. So instead of coding I10 and N18.9, we will code I12.9 and N18.9 (CKD unspecified Stage)

The answer for Second example is F41.9 (anxiety), and F32.A (depression). Here we will not presume the linkage between Anxiety and depression until physician does not give.

Explanation: As per ICD 10 CM Guidelines,

The word “with” or “in” should be interpreted to mean “associated with” or “due to” when it appears in a code title, the Alphabetic Index (either under a main term or subterm), or an instructional note in the Tabular List.

Here in the example, it appeared in coded title.

Caution:
These conditions should be coded as related even in the absence of provider documentation explicitly linking them, unless the documentation clearly states the conditions are unrelated or when another guideline exists that specifically requires a documented linkage between two conditions (e.g., sepsis guideline for “acute organ dysfunction that is not clearly associated with the sepsis”).