With more than 71,000 ICD-10 codes this year, your diagnosis coding can be more confusing than ever. One key to limiting that confusion is to know how to easily identify and when to use combination codes. These codes link symptoms, manifestations or complications with a particular diagnosis. Use them correctly, and you’ve got medical necessity in the bag. Get them wrong, and payers will deny your claims and your reimbursement.
In some cases, ICD-10-CM offers one code to represent two diagnoses. This is particularly effective when your practitioner documents a disease and an associated manifestation, such as diabetes mellitus and a resulting neuropathy. This is ICD-10’s attempt to limit the number of codes you have to report.
There’s an easy way to tell when you’re dealing with combination diagnoses. You’ll find them in the Alphabetic Index by locating the primary condition and then using the subterm entries to narrow your code search. For instance, such subterms might include “with,” “due to,” “in” or “associated with.” These should be pretty clear indicators that you’re working with a combination code. In the Tabular List, you will find additional clues by reviewing the “includes” and “excludes” notes.
Similar to the subterms in the Alphabetic Index, the Tabular notes will let you know when combinations codes are appropriate. For example, the notes under E10.21 (Type 1 diabetes mellitus with diabetic neuropathy) state that it includes “Type 1 diabetes mellitus with intercapillary glomerulosclerosis” and “Type 1 diabetes mellitus with Kimmelstiel-Wilson disease.” Using words like “with” in the notes to tie together two related diagnoses is a clear indicator of a combination code.
When considering these codes, you should use them only when they meet both of the following criteria:
- The Alphabetic Index specifically lists them to match your primary diagnosis.
- The code fully identifies the diagnostic conditions your clinician documented.
Example: Your physician notes in the medical record that his patient has rheumatoid arthritis of the right ankle and foot, as well as rheumatoid polyneuropathy. When you search the Alphabetic Index for “arthritis, rheumatoid,” you find a cross-reference — “see Rheumatoid, polyneuropathy” — that points you to M05.57-. To track down the most specific diagnosis code possible, you go to the Tabular Index and look for M05.57. There, you find the best code for this case, M05.571 (Rheumatoid polyneuropathy with rheumatoid arthritis of right ankle and foot).
This code completely represents the patient’s condition. So you only need the one code to match the documented diagnosis for this encounter.
In particular, you’ll find combination codes frequently used with such diagnoses as diabetes — E10 (Type 1), E11 (Type 2), and E13 (Other specified) — and poisoning by, adverse effects of, and underdosing of drugs (T36-T50), among others.
And if you try to report separate diagnosis codes instead of the combination, your claim has a higher chance of getting denied. ICD-10 instructions state that you should use the combination code whenever possible and it completely details the patient’s condition. So you can be sure payers will hold you to that when deciding which of your claims to pay.
Take Aways:
- Use an available combination code whenever it appropriately defines your patient’s condition.
- Look for combination codes particularly with diabetes and poisoning by medication diagnoses.
- Failure to use an available combination code likely will lead to claim denials.