Mono Test Specimen Type
No, the mono test (Monospot/heterophile antibody test) is not a swab test—it requires a blood sample (serum). 1
Standard Specimen Collection for Mono Testing
The Infectious Diseases Society of America specifies that the Monospot test requires 5 mL of serum collected in a clot tube at room temperature, transported within 2 hours. 1 This is a blood draw, not a throat swab.
Why Blood and Not a Swab?
The Monospot test detects heterophile antibodies circulating in the bloodstream that develop during EBV infection, making serum the only appropriate specimen type. 2 While EBV can be detected in throat secretions, this finding does not confirm acute infection since the virus can persist in the throat for weeks to months after infection. 3
When Swabs ARE Used for Pharyngitis
Throat swabs are used for different pathogens causing pharyngitis, not for mono:
- Rapid antigen tests for Streptococcus pyogenes (strep throat) use pharyngeal swabs 1, 4
- HSV detection from pharyngeal lesions uses swabs 1
- Bacterial cultures for other organisms use throat swabs 1
Complete Diagnostic Algorithm for Suspected Mono
Initial testing approach:
- Collect blood for Monospot test (heterophile antibody) 1, 3
- Obtain complete blood count with differential to look for lymphocytosis with atypical lymphocytes 3, 5
If Monospot is positive:
If Monospot is negative but clinical suspicion remains high:
- Perform EBV-specific serologic testing on the same serum sample for VCA IgM, VCA IgG, and EBNA antibodies 1, 3, 2
- Alternatively, repeat Monospot on a new serum specimen 7-10 days later, as heterophile antibodies develop over time 1, 2
Critical Pitfalls to Avoid
False-negative Monospot tests occur in up to 10% of cases, particularly in:
Never rely solely on a negative Monospot to rule out infectious mononucleosis when clinical suspicion is high—proceed immediately to EBV-specific antibody testing. 3, 2