CPT 90791 + ICD-10 F31.9: Bipolar disorder, unspecified
Psychiatric diagnostic evaluation billed with Bipolar disorder, unspecified — documentation requirements, denial reasons, modifiers, and reimbursement context.
CPT Code
90791
Psychiatric diagnostic evaluation
ICD-10 Code
F31.9
Bipolar disorder, unspecified
Compatibility Notes
Used for initial evaluations where bipolar disorder is suspected or newly presenting. F31.9 (unspecified) is appropriate during the diagnostic evaluation phase before the episode type and severity have been established. After the evaluation, update to a more specific bipolar code (e.g., F31.0–F31.81) in subsequent sessions. Most payers allow 90791 once per year per provider without prior authorization.
Documentation Required
- ✓Face-to-face evaluation with documented psychiatric and mood history
- ✓Family history of mood disorders
- ✓Current and past manic, hypomanic, and depressive episode documentation
- ✓Substance use screening (critical for bipolar differential)
- ✓Risk assessment including suicide and homicide
- ✓Plan for diagnostic clarification (mood charting, collateral, medication consideration)
Common Denial Reasons
- ✗F31.9 used long-term without ever refining to a specific subtype — may trigger audit after the third session
- ✗90791 billed more than once in a benefit year by the same provider — check payer policy
- ✗Evaluation notes lack the breadth expected for a psychiatric diagnostic evaluation (reads like a therapy note)
Applicable Modifiers
Reimbursement Notes
OON UCR for 90791 is $175–$350. Commercial plans typically reimburse 50–70% of UCR. This is one of the highest single-session reimbursements available to outpatient therapists and should be billed for every new patient intake.
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