We Loaded 2.5 Million Medical Codes Into a Database. Here's Why.

Before we built a single AI feature, we built a database. Not because databases are exciting, but because every claim denial we've ever seen traces back to a gap in the underlying code data. You can't catch what you can't look up.

Here's what's in it and why each piece matters.

The Five Tables

ICD-10: 74,719 Diagnosis Codes

ICD-10-CM is the diagnosis coding system used on every claim submitted to every payer in the US. The 2025 edition has 74,719 codes. Each code maps to a specific diagnosis — F32.1 is major depressive disorder, single episode, moderate. F41.1 is generalized anxiety disorder. F43.10 is post-traumatic stress disorder, unspecified.

We store the full code, description, valid billing indicator, and the code's position in the ICD-10 hierarchy. The hierarchy matters because some payers require a specific level of specificity — billing F32 (unspecified depression) when F32.1 is available can trigger a denial for insufficient diagnosis detail.

NCCI PTP: 2,387,727 Bundling Edits

The NCCI Procedure-to-Procedure edit table defines which CPT code pairs cannot be billed together without a modifier. With 2.38 million pairs, this is the largest table in our database and the most important one for denial prevention.

Each record contains the column-one code, the column-two code, the modifier indicator (0 = modifier not allowed, 1 = modifier allowed), the effective date, and the deletion date. When a claim contains two CPT codes, we check this table. If the pair is flagged and no valid modifier is present, the claim is blocked before submission.

CPT RVU: 15,804 Procedure Codes

The CPT RVU (Relative Value Unit) table is published by CMS and defines the payment weight for every CPT code. Each record contains the work RVU, practice expense RVU, malpractice RVU, and total RVU. Multiply the total RVU by the Medicare conversion factor ($33.89 in 2025) and you get the national payment rate.

We use this table for two things: validating that the billed amount is within a reasonable range for the code, and flagging claims where the RVU-based expected payment is significantly higher than what the practice has been collecting — which often indicates a coding error.

MUE: 15,095 Medically Unlikely Edits

Medically Unlikely Edits (MUEs) define the maximum number of units that can be billed for a single CPT code on a single date of service. CPT 90837 (60-minute psychotherapy) has an MUE of 1 — you can't bill it twice in one day for the same patient. CPT 90832 (30-minute psychotherapy) also has an MUE of 1.

Billing above the MUE triggers an automatic denial. Our engine checks every line item against the MUE table before the claim goes out. If a claim has 2 units of 90837, it gets flagged and corrected.

HCPCS: 8,727 Supply and Service Codes

HCPCS Level II codes cover supplies, equipment, and services not in the CPT system — things like telehealth originating site fees (Q3014) and certain behavioral health services. Mental health practices billing for telehealth services need these codes on specific claim types.

We store the full HCPCS code set with coverage indicators and payer-specific billing requirements.

How They Work Together

When a claim is generated, our engine runs it through all five tables in sequence. First, every ICD-10 code is validated for specificity and valid billing status. Then every CPT pair is checked against the NCCI PTP table. Then every line item's units are checked against the MUE table. Then the billed amounts are compared against RVU-based expected rates. Finally, any HCPCS codes are validated for the specific payer.

A claim that passes all five checks goes out. A claim that fails gets a specific, actionable correction instruction — not a vague error message, but the exact rule that was violated and what needs to change.

That's 2,505,007 records standing between your claim and a denial.