We all know medical billing is a mess.
Every time we open a letter from our insurance company, a hospital, or a doctor’s office, we come face to face with a mountain of numbers, codes, and jargon that feel intentionally confusing. The charges often have little resemblance to what was actually paid—or what we’re expected to pay.
But here’s the thing: it’s even more complicated than you think.
The Hidden Complexity of Medical Claims
Let’s break it down.
As of 2025:
- There are 11,321 CPT codes—those 5-digit identifiers that doctors and hospitals use to define procedures and services.
- There are 69,832 ICD-10 diagnosis codes, used to describe everything from a cough to a coma.
Every outpatient claim must include at least one procedure code and one diagnosis code. That means the most basic claim still leaves room for 3.3 billion possible combinations of codes.
And most claims? They’re not basic.
Many include five or more codes. Even if we assume that only 10% of these codes are used frequently, the number of potential five-code combinations is a mind-boggling 293 billion trillion—a number that rivals the grains of sand on Earth.
Yes, really.
And yes, some of these codes are oddly specific:
- W61.62: Struck by a duck
- Y92.253: Injury in an opera house
Welcome to American healthcare and also welcome to the world of medical codes.
As of 2025, there are:
- 11,321 CPT codes—used to report procedures or services
- 69,832 ICD-10 codes—used to identify diagnoses
Even the simplest outpatient claim must include at least one procedure code and one diagnosis code. That’s nearly 3.3 billion potential code combinations.
Most claims have more than two codes. Many have five or more. If we assume that only 10% of these codes are used frequently, the number of possible five-code combinations is an astonishing 293 billion trillion.
That’s roughly equal to the number of grains of sand on Earth.
Yes, Some of the Codes Are Wild
Just to give you a sense of how bizarre it gets:
- W61.62: Struck by a duck
- Y92.253: Injury sustained in an opera house
This is the level of detail—and absurdity—that lives inside the modern medical claims system.
So How Did It Get So Complicated?
That’s the million-dollar question. Why are medical bills so complex? Why does it feel like a labyrinth every time you try to make sense of a claim?
The truth is, there are good reasons and not-so-good reasons. Some of the complexity comes from efforts to increase accuracy and fairness. Other layers are artifacts of outdated processes, regulatory bloat, or business models built on confusion.
