In the face of the impending ICD-10 implementation, you might be afraid of getting lost in the mire of new codes, left to wander the metaphorical sewers as you scavenge for whatever relevant codes you can find. And when October 1 rolls around, you very well could stumble upon a shattered glass jar and four baby turtles, and—wait a second; this sounds a lot like the plot of a ’90s movie about life-sized teenage reptiles.

Even though ICD-10’s history is tumultuous—not unlike an action movie plot—the truth is that ICD-10 implementation is far from mutant ninja fiction. You might find the complexity of the new coding system daunting; but don’t worry, you’re not alone. Even Master Splinter himself would probably grimace at the thought of taking on this challenge. But here’s the good news: it doesn’t have to be painful. With a set process in place, determining the most accurate ICD-10 code—no matter the situation—can become as second-nature as ordering your favorite deep-dish pizza. All kidding aside, here are three simple steps to determine the right diagnosis code, as adapted from this article:

1. Cowabunga, Index!

To narrow down your ICD-10 code options for a particular diagnosis, start by looking up the main term in the alphabetic index. Once you’ve chosen the most relevant main term, find sub-terms to help you boil down your diagnosis even further. To make sure you consider all possibilities, look for additional cues in the instructional notes (e.g., “see,” “see also,” “with,””without,” “due to,” and “code by site”).  

2. Totally Tabular

After you find the main term in the alphabetic index, you might land on a very general version of the code. Such codes typically include labels like “unspecified,” and most of them feature only three or four alphanumeric characters. In some cases, these codes are the most accurate codes available; in others, you might have to keep digging. To be sure you find the most specific code possible, verify the code within the tabular list, which:

  • Organizes the codes by disease and injury.
  • Accounts for severity.
  • Includes all possible coding options for each condition (these codes may contain anywhere from three to seven characters).
  • Denotes any applicable exclusions—which indicate when codes can or cannot be used together—for each block of codes. Here, CMS covers the two types of exclusion instructions:
    • “Excludes1: It means ‘NOT CODED HERE!’ An Excludes1 note indicates that the code excluded should never be used at the same time as the code above the Excludes1 note.”
    • “Excludes2: A type 2 excludes note represents ‘Not included here.’ An excludes2 note indicates that the condition excluded is not part of the condition it is excluded from but a patient may have both conditions at the same time. When an Excludes2 note appears under a code it is acceptable to use both the code and the excluded code together.”

Pay close attention to these types of instructions as you peruse the tabular index, because they often contain guidance that is key to pinpointing the most detailed, accurate, and complete diagnosis code available.

3. Mega Guideline Guidance

Think you’ve boiled down your code to the most specific version? Bodacious! Now, on to the final step: reviewing the ICD-10 manual for chapter-specific coding guidelines. At the beginning of each chapter, you’ll find notes with additional instructions related to that group of codes—for example, whether you need to consider reporting any supplementary codes such as external cause codes. In addition to these notes, the manual includes important sequencing order guidelines. Depending on the condition you’re treating—and its related causation—the sequencing order of the codes will vary. Additionally, you should review this CDC document that covers “conventions, general coding guidelines, and chapter specific guidelines.”


If you follow these three steps, you’ll reduce your chances of encountering coding errors. And after some practice, you might even find yourself a master in your own right—able to code W59.22XA, “struck by turtle, initial encounter,” faster than you can say, “Pepperoni, please!”