Introduction
As far as documentation and coding are concerned, it is highly important for a medical billing professional to pay deep attention to detail. By using the proper codes, healthcare providers will be able to receive appropriate reimbursements for the services they provide. To help insurance companies and Medicare make the best price-setting decisions, the M-codes are important codes that are needed.
This article focuses on the M8 modifier—a unique code that impacts reimbursement for blood gas tests when claims are submitted. For billing specialists and healthcare providers involved in respiratory care, Durable Medical Equipment (DME), and oxygen therapy, a solid understanding of the M8 modifier is essential.
What is M8?
The M8 modifier carries a specific meaning in medical billing: “We do not accept blood gas test results when the test was conducted by a medical supplier or taken while the patient is on oxygen.”
This straightforward definition has important implications for healthcare providers and DME suppliers. Insurance companies and Medicare use the M8 modifier when the claims get rejected. This includes blood gas test results obtained from unauthorized sources or under conditions that may compromise their accuracy.
Why Does M8 Exist?
Blood gas tests measure oxygen and carbon dioxide levels in the blood, providing the necessary information about a patient’s respiratory function. These tests help determine whether a patient needs supplemental oxygen and what level of oxygen therapy might be appropriate.
Insurance companies and Medicare created the M8 modifier to ensure they only pay for oxygen therapy based on accurate, unbiased test results.
For these test results to be reliable, they must be:
- Conducted by qualified healthcare professionals
- Performed in appropriate clinical settings
- Done when the patient is breathing room air (not receiving supplemental oxygen)
Where M8 Typically Applies
Setting | Why M8 Might Apply |
DME supplier locations | Potential conflict of interest (suppliers might benefit from prescribing oxygen) |
Home healthcare visits | Tests might be done while patient remains on existing oxygen therapy |
Non-laboratory settings | Lack of proper testing equipment or conditions |
Mobile testing services | Concerns about quality control and proper procedures |
Billing Challenges & Denials
When providers or billing specialists don’t properly understand M8, various problems can occur:
Common Billing Issues
- Submission of test results from ineligible sources
- Tests performed by oxygen suppliers
- Tests done in non-clinical settings
- Results from unqualified personnel
- Inadequate documentation
- No clear record shows the patient was off oxygen during testing.
- Missing information about who performed the test
- Incomplete details about testing conditions
- Timing problems
- Tests performed too soon after removing oxygen
- No documentation of how long oxygen was discontinued before testing
Impact of M8 Denials
When claims trigger an M8 denial, several consequences follow:
- Delayed reimbursement for services and equipment
- Additional administrative work to appeal or resubmit claims
- Potential need for patients to undergo repeat testing
- Strain on patient-provider relationships
- Possible interruptions in needed oxygen therapy
Who Can Perform Accepted Blood Gas Tests?
Understanding who can perform blood gas tests that won’t trigger M8 denials is essential:
Approved Sources | Non-Approved Sources |
Hospital laboratories | DME suppliers |
Independent clinical laboratories | Home medical equipment companies |
Physician’s offices with proper equipment | Testing while patient is on supplemental oxygen |
Pulmonary function labs | Mobile testing units affiliated with suppliers |
Solutions and Best Practices
Various steps can be taken by healthcare providers and billing specialists to avoid M8 denials:
1. Verify Test Sources and Conditions
Before submitting claims for oxygen therapy based on blood gas results:
- Certify that tests performed were approved by healthcare providers
- Verify the testing facility is independent from DME suppliers
- Make sure that documentation clearly states about the patient was not receiving oxygen during testing
2. Implement Staff Training
Create a training program that covers:
- What the M8 Modifier Means and How It Affects Billing
- Which blood gas test sources are accepted by insurers
- Appropriate documentation requirements for testing conditions
- How to assess M8 issues before claim submission
3. Use a Documentation Checklist
Develop a simple checklist that includes:
- Test performed by qualified healthcare professional
- Testing location is an approved facility
- Patient off oxygen for appropriate time before testing (typically 20-30 minutes)
- Time off oxygen clearly documented
- Testing conditions (room air) clearly noted
- Name and credentials of person performing test recorded
4. Establish Relationships with Approved Testing Sources
Work closely with:
- Independent laboratories
- Hospital outpatient departments
- Pulmonologist offices
- Primary care providers with appropriate testing equipment as these relationships make sure that patients can easily access properly conducted tests that won’t trigger M8 denials.
Real-World Example
Case Study: Avoiding M8 Denials
Situation: Mrs. Garcia, a 68-year-old patient with COPD, needed to qualify for home oxygen therapy. Her DME supplier suggested performing a blood gas test during their home delivery visit while briefly removing her existing oxygen.
Problem: The claim was denied with an M8 modifier because:
- The test was conducted by the DME supplier.
- There was inadequate documentation about how long Mrs. Garcia was off oxygen.
- The testing environment wasn’t a clinical setting.
Solution: The provider took these steps:
- Scheduled Mrs. Garcia for blood gas testing at an independent pulmonary lab.
- Ensured she remained off supplemental oxygen for 30 minutes before testing.
- Obtained detailed documentation of testing conditions.
- Submitted a new claim with proper documentation.
Result: The new claim was approved without an M8 denial, and Mrs. Garcia received her needed oxygen therapy with proper coverage.
Lessons Learned:
- Always use independent testing sources
- Document oxygen status clearly
- Keep detailed records of testing conditions
- Educate patients about proper testing procedures
Important Documentation Elements
Documentation Element | What to Include | Why It Matters |
Testing Personnel | Name, credentials, employer | Confirms qualified tester not affiliated with DME supplier |
Testing Location | Facility name, address, type | Verifies appropriate clinical setting |
Patient Oxygen Status | Time oxygen was removed, duration off oxygen | Proves test was done under room air conditions |
Test Results | Full results including time, date, and room air notation | Provides complete clinical picture |
Ordering Provider | Name of physician ordering the test | Shows medical necessity and proper ordering |
Conclusion
Understanding the M8 modifier is essential for healthcare providers and billing specialists who deal with respiratory care and oxygen therapy services. By recognizing what triggers M8 denials—blood gas tests from medical suppliers or while patients are on oxygen—providers can take steps to ensure proper testing and documentation.
Key points to remember:
- Blood gas tests must come from qualified, independent sources
- Patients should be off oxygen for an appropriate period before testing
- Clear documentation of testing conditions is essential
- Working with approved testing facilities reduces denial risk
By initiating these best practices around blood gas testing and documentation, healthcare providers can help reduce claim denials, increase reimbursement rates, and make sure that patients receive proper and timely access to needed oxygen therapy.
Need Help With Medical Billing?
If your firm is facing any challenges with M8 denials or any other medical billing issues, our expert team can help. We give training, documentation tools, and billing support to make sure your claims are processed correctly without any issues or delays.
Contact us today for more information.