A UnitedHealthcare denial lands on your desk citing "medical necessity not established." Your instinct is to write a thorough letter explaining everything. That instinct will produce a 4-page letter that gets ignored.
Disclaimer: This is educational, not billing, legal, or medical advice. Payer policies change frequently and your situation may differ from the examples here. Always verify current requirements with your payer's most recent published policy and consult qualified billing or compliance professionals. Use this information at your own risk.
Match Your Letter to the Exact Denial Reason
This sounds obvious, but most appeal letters fail because they argue the wrong thing. Payers categorize denials — medical necessity, non-covered service, experimental/investigational, documentation insufficient. Each requires a different argument.
Pull the denial notice and find the specific reason code. If it's CO-50 (medical necessity), your letter needs to show clinical appropriateness using the payer's own coverage criteria. If it's CO-197 (pre-certification absent), you're making a procedural argument about why retro-auth applies, not a clinical one. Conflating these is the most common appeal mistake.
For genetic testing and oncology claims, you're most often fighting a medical necessity denial. The payer's reviewer said the clinical information you submitted didn't satisfy their policy. That means your appeal has one job: show that the clinical information does satisfy their policy, or that their policy is inconsistent with accepted clinical standards.
The Structure That Gets Read
Appeals reviewers process dozens of letters a day. They skim. Your letter needs to lead with the conclusion, not build to it.
First paragraph: State what you're appealing, reference the denial date, and assert your conclusion upfront. Example: "We are appealing the January 14, 2026 denial of CPT 81479 for [patient initials, DOB, member ID]. The denial should be reversed because the submitted documentation satisfies the criteria set forth in [payer]'s Molecular Diagnostic Testing Policy, effective [date], and is consistent with NCCN Clinical Practice Guidelines Category 2A."
Second paragraph: Lay out the clinical facts — diagnosis code(s), the specific clinical indication that justifies the test or drug, any prior treatments and outcomes, and the treating physician's clinical rationale. Keep this to a paragraph or two. Use bullet points for test history or prior treatment steps. Don't editorialize.
Third section: Cite the policy. Quote the relevant coverage criteria verbatim from the payer's published medical policy or LCD. Then show, criterion by criterion, that the patient meets each one. This is where most letters fall short — they describe the patient's situation in general terms instead of walking through the payer's own checklist.
Fourth section (if applicable): Cite external authority. NCCN guideline designation (category and indication), NCD coverage criteria, peer-reviewed literature. Attach the specific pages, not just the full document. If you're citing NCD 90.2 for next-generation sequencing in cancer, include the exact coverage criteria text.
Closing: State what you're requesting and the timeline you expect a response within. Reference the applicable federal or state appeal rights (42 CFR §405.960–405.978 for Medicare; 45 CFR §147.136 for ACA-compliant plans; 29 USC §1133 for ERISA plans).
What to Attach
- The payer's denial letter (to establish the administrative record)
- The treating physician's letter of medical necessity — specific to this patient, not a form letter
- The relevant pages from the payer's own coverage policy (highlight the criteria you're addressing)
- NCCN guideline pages with the indication highlighted
- Pathology or lab results that establish clinical context
- Prior treatment documentation if step therapy or failure of alternatives is relevant
Don't attach a 200-page academic literature dump. Attach the two or three studies that directly support the specific indication, and cite them in the letter body.
Cigna and Aetna Have Different Preferences
Cigna's internal appeal process goes through Cigna's Appeals and Grievances team, and they are strict about submission format and deadlines. If you're using Cigna for HCP (their provider portal), you can submit appeals electronically. They will bounce an incomplete submission — missing member ID, missing treating physician signature — on procedural grounds before a reviewer ever reads it.
Aetna's process is similar but they've published specific documentation requirements by service category. For genetic testing appeals, Aetna's oncology medical policies cite MCG (Milliman Care Guidelines) criteria heavily. If you know the MCG reference they're applying, address it directly.
For Medicare Advantage plans, the appeals process follows Part C timelines (generally 60 days from denial to request a redetermination). The plan must decide within 7 days for standard appeals and 72 hours for expedited. Miss that distinction and you'll get a procedural rejection.
Checklist Before You Submit
- Denial reason code identified and letter addresses it directly
- Member ID, date of service, CPT code, and treating provider NPI all match the denial notice exactly
- Payer's coverage criteria quoted verbatim and addressed point-by-point
- Physician letter is patient-specific (not a template)
- NCCN or other guideline citation attached with relevant pages
- Submission deadline confirmed and met (typically 60–180 days from denial date)
- Delivery method documented (portal confirmation number, fax confirmation, certified mail receipt)
Sources
- 42 CFR §405.960–405.978 (Medicare administrative appeals process)
- 45 CFR §147.136 (internal claims and appeals — ACA-compliant plans)
- 29 USC §1133 (ERISA full and fair review)
- ACA §2719 (independent external review for non-grandfathered plans)
- CMS NCD 90.2 (next-generation sequencing in cancer)
- NCCN Clinical Practice Guidelines (NCCN.org) — category designations by indication