Coding rules: combination categories, history-of and causal wording

One code, or a cluster?

One code or a cluster? It depends on combination categories, history, and the words the clinician used.

Which words link

Words matter. Due to, caused by and arising from show the practitioner made a causal link. With, after, in and following are ambiguous. When it isn't clear whether a causal relationship is meant, code each condition separately and don't link them in a cluster.

• Clear · due to · Due to, caused by, arising from: the practitioner made a causal link.
• Ambiguous · with, after · With, after, in and following are ambiguous.
• The rule · Separate · When ambiguous and unclear, code each condition separately and do not link them in a cluster.

Use the one code where it exists

Where the classification has a combination category, use it. Glaucoma due to eye inflammation is one precoordinated code. Where it doesn't, link stem codes in a cluster: chronic kidney disease stage four with hypertensive renal disease, with essential hypertension as another condition.

• Precoordinated · 9C61.24 · Glaucoma secondary to eye inflammation has its own code: glaucoma due to eye inflammation.
• Cluster · GB61.4/BA02 · Chronic kidney disease, stage 4, linked to hypertensive renal disease; essential hypertension is another condition.

Diabetic cataract, and the rest

Diabetic cataract is the main condition, with the type of diabetes coded also, linked in a cluster. The hypertension is not linked to either, so it stays outside the cluster, as an other condition.

• Main condition · 9B10.21/5A10 · Diabetic cataract, with a code also for the type of diabetes.
• Other · BA00 · Hypertension is not linked to the cataract or diabetes: it is an other condition.

Two acceptable ways

For a history of, WHO accepts two ways. The history code alone. Or the history code clustered with the code for the previous disease, which describes the documented concept fully. The history code always comes first.

• Option 1 · QC40.0 · The history code alone captures personal history of cancer of the digestive organs.
• Option 2 · QC40.0/2B90.3Z · Clustered, it describes the history of sigmoid colon cancer in full. History comes first.

Check yourself

Pause and think. The classification has a combination category for glaucoma due to eye inflammation. What do you do? The answer: Use the combination category as one code. Where the classification has a combination category, use it. Where it does not, link stem codes in a cluster.

• Build a cluster of two stem codes
• Code each condition separately
• Code only the inflammation
• Use the combination category as one code

Keep these in mind

Due to links. With, after, in and following do not. Use a combination category where one exists. Cluster only what is documented as linked. And history comes first in a history cluster.

• Due to links; with, after, in, following do not
• Use a combination category where one exists
• Cluster only what is documented as linked
• History comes first in a history cluster