What Medical Billing and Denial Codes Mean

Modifier 91: Meaning and Use in Laboratory Billing

Find out when modifier 91 applies to repeat laboratory tests, when it should not be used, and what records support its use on medical claims.

CO 97 Denial Code: Meaning and Checks for Lab Claims

Find out what the CO 97 denial code means, why it appears on lab claims, and what to check before correcting a claim or challenging an adjustment.