The autocoder reads the diagnoses out of the documentation. It selects the most specific code the documentation supports. It does not infer a diagnosis from a medication list, a vital sign, or a comorbidity.

## Which diagnosis becomes primary

The primary diagnosis is the condition that explains why the provider performed the procedure. The autocoder prefers a definitive diagnosis over a symptom when the documentation carries both. When a definitive diagnosis is documented, an integral symptom or site-pain code is dropped rather than demoted. For example, abdominal pain (R10.x) drops when the record documents appendicitis.

When sources disagree about the procedure and its findings, the autocoder uses the highest-authority source. The order is the operative report, then the post-anesthesia note, then the intraoperative anesthesia record, then the pre-anesthesia evaluation.

Supporting diagnoses follow the primary. Comorbidities that support the ASA physical status come first among them. Family history codes (Z80-Z84) and status codes never take the primary slot.

## Combination codes

When the record documents two conditions that have a single ICD-10-CM combination code, the autocoder collapses them into that code. The four collapses are:

| Documented together | Result |
|---|---|
| Hypertension (I10) with chronic kidney disease (N18.x) | I12.0 or I12.9 |
| Hypertension (I10) with heart failure (I50.x) | I11.0 |
| Hypertension with both of the above | I13.0 or I13.2 |
| Unspecified type 2 diabetes (E11.9) with chronic kidney disease | E11.22 |

The chronic kidney disease stage code and the heart failure code stay on the claim as additional codes. If the combination code was already present, the autocoder drops the redundant standalone code instead. The combination code takes the primary slot when one of its members occupied that slot. When the documentation states that the two conditions are unrelated, the autocoder keeps the separate codes.

Every collapse produces a **Combination Diagnosis Code Applied** alert (`icd_combo_collapsed`, INFORMATIONAL, default severity 3). It is an audit record, not a question.

## Laterality and specificity

The autocoder matches laterality to the documentation. When the record does not state a side, it uses the unspecified code. It never infers anatomy, laterality, or an initial-versus-subsequent encounter from a code lookup alone.

## Diagnoses per line

The `max_icd_per_line_item` processing rule limits each line item to four diagnosis codes on anesthesia claims. Your facility configuration controls the limit. Contact your Hank representative to change it.

## Related alerts

- **Primary Diagnosis Not Explicitly Attested as Reason for Procedure** (`primary_icd_not_attested`, HARDSTOP, default severity 7). This alert asks a coder to confirm that the record states the primary diagnosis as the reason for this procedure. It fires when the only source is a problem list, past medical history, a family or personal history entry, a medication or billing list, or a history of present illness with no stated link. Your facility configuration controls this alert through `claimValidation.checks.primaryIcdAttested`.
- **Diagnosis Validation Returned No Result** (`icd_verdict_empty`, COMPLIANCE, default severity 5). The validation step returned no verdict. The diagnosis codes ship as extracted, so read them against the documentation.

## How this reaches you

What happens next depends on how your organization consumes HANK CODES. In HANK Claim Maker, a HARDSTOP alert places the claim in the review queue your administrators configured for it. Organizations that consume the coding API directly decide in their own workflow which alerts pause a claim, who reviews them, and when a claim is released.