Major criteria
Minor criteria
How it's calculated
Definite infective endocarditis requires 2 major criteria, OR 1 major plus 3 minor criteria, OR 5 minor criteria. Possible infective endocarditis requires 1 major plus 1 minor, OR 3 minor criteria, without meeting the definite threshold.
Classification logic
| Criteria met | Classification |
|---|---|
| 2 major, or 1 major + 3 minor, or 5 minor | Definite |
| 1 major + 1 minor, or 3 minor | Possible |
| Fewer than the above | Rejected |
Clinical use
- A clinical-pathological classification framework, not a purely numeric risk score — used alongside echocardiography, blood cultures, and clinical assessment to support (not replace) the diagnosis of infective endocarditis.
- A 'possible' classification does not exclude endocarditis — it prompts continued clinical suspicion, further testing (e.g. repeat/TEE echocardiography), and close follow-up.
- Pathological criteria (organisms demonstrated on a vegetation or histology at surgery/autopsy) independently establish 'definite' endocarditis and are not captured in this simplified clinical-criteria calculator.
- A firm alternative diagnosis, resolution of the syndrome with 4 days of antibiotics or less, or no pathological evidence at surgery can override a 'possible' or 'definite' classification — this tool reflects clinical criteria only.
Frequently asked questions
What is the Modified Duke Criteria used for?
It provides a structured framework combining blood culture, echocardiographic, and clinical findings to classify the likelihood of infective endocarditis as definite, possible, or rejected.
Does a 'possible' classification rule out endocarditis?
No — it means the diagnosis remains uncertain and should prompt continued clinical suspicion, further testing, and close follow-up rather than being dismissed.
Are pathological (surgical/autopsy) criteria included here?
No — this calculator implements the clinical criteria only; a pathological finding of organisms in a vegetation or abscess independently establishes definite endocarditis regardless of the clinical criteria.
Can this classification change over time?
Yes — new blood culture results, a follow-up echocardiogram, or the emergence of an alternative diagnosis can shift the classification as more information becomes available.
References
- Li JS, Sexton DJ, Mick N, et al. Proposed modifications to the Duke criteria for the diagnosis of infective endocarditis. Clin Infect Dis. 2000;30(4):633-638.
- Durack DT, Lukes AS, Bright DK. New criteria for diagnosis of infective endocarditis: utilization of specific echocardiographic findings. Duke Endocarditis Service. Am J Med. 1994;96(3):200-209.