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    Patent Pending

    POSSUM for Operative Morbidity and Mortality Risk

    Estimates morbidity and mortality for general surgery patients.


    Use values at the time of surgery, not admission.

    NOTE: The POSSUM should not be used for trauma patients.

    When to Use
    Why Use

    Patients undergoing emergency and elective general surgical procedures.

    • The Physiological and Operative Severity Score for the enUmeration of Mortality and morbidity (POSSUM) assesses morbidity and mortality for general surgery.
    • It can be used for both emergency and elective surgery.
    • The original POSSUM was modified by researchers in Portsmouth who derived a more accurate prediction of mortality, and the P-POSSUM model is now more commonly used to calculate the mortality component.
    • The POSSUM data set excludes trauma patients, so POSSUM should NOT be used to predict morbidity and mortality after trauma surgery.
    • The POSSUM should NOT dictate the decision to operate, which is a clinical decision.
    • Physiological score should be calculated at the time of surgery, not at the time of admission.
    • The definitions of surgical procedures are guidelines only. Not all procedures are listed, and the closest approximation should be selected.
    • The POSSUM may overestimate risk in hepatopancreaticobiliary surgery.

    The POSSUM calculates risk for operative morbidity and mortality, which can be used to help patients and family members make informed decisions about surgery.

    Similar / alternative tools:

    • There are procedure-specific models for colorectal surgery (CR-POSSUM), vascular surgery (Vascular-POSSUM), and esophagogastric surgery (O-POSSUM, O for oesophagogastric).
    • APACHE II is a similar assessment tool but is applied to intensive care patients and only assesses the risk of mortality.
    • The Surgical Apgar Score (SAS) offers similar estimates for morbidity and mortality.
    • The POSSUM is more comprehensive than the SAS (which is calculated based on 3 parameters), but the SAS is more objective.
    • The SAS uses intraoperative parameters exclusively, whereas the POSSUM uses preoperative parameters.
    • The ACS NSQIP risk calculator is a newer, similar assessment. It has not yet been as rigorously validated as the POSSUM.
    • Other disease-specific scores may be used to assess risk, e.g. Revised Cardiac Risk Index for Pre-Operative Risk.
    Physiological score
    No failure
    Diuretic, digoxin or angina/hypertension meds
    Peripheral edema, warfarin, or borderline cardiomegaly on chest X-ray (CXR)
    Raised jugular venous pressure, or cardiomegaly on CXR
    No dyspnea
    Exertional dyspnea or mild COPD on CXR
    Limiting dyspnea or moderate COPD on CXR
    Dyspnea at rest or fibrosis/consolidation on CXR
    mm Hg
    × 10³ cells/µL
    Atrial fibrillation (HR 60-90)
    5 ectopic beats/min, Q waves or ST/T wave changes
    Any other abnormal rhythm
    Operative severity score
    Minor (serous fluid)
    Local pus
    Free bowel content, pus or blood
    Primary only
    Lymph node mets
    Distant mets
    Emergency (within 24h), resuscitation >2h possible
    Emergency (within 2h)


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    Next Steps
    Creator Insights
    Dr. Graham Copeland

    From the Creator

    Why did you develop the POSSUM? Was there a clinical experience that inspired you to create this tool for clinicians?
    I developed it originally to act as an audit aid for the retrospective review of adverse outcomes and then realised that it could be used as a measure of surgeon quality.
    Are there any pearls, pitfalls, or tips you have for surgeons using POSSUM to assess operative risk for their patients?
    Its main use is in pre-op assessment to give patients and relatives a more realistic expectation of the post-operative course.
    Are there cases when it has been applied, interpreted, or used inappropriately?
    I have never heard of anyone using it as a 'futility index' (i.e., a reason to avoid a necessary surgery), but that remains a potential risk.
    How do you think the POSSUM compares to other similar assessments?
    I have looked at the ACS NSQIP risk calculator and have found that, as it depends on surgeon-declared data, it often under-estimates risk, as compared to coded-derived data, which may be a more independent assessment. If these underestimated predictions are communicated to patients, this may cause a future potential problem.

    About the Creator

    Graham Copeland, MBBS, is a consultant general surgeon at Broadgreen Hospital in Liverpool. Graham has been an advisor to the Healthcare Commission and the National Institute of Clinical Effectiveness in the United Kingdom. Dr. Copeland's research focuses on clinical audits and outcome measures in surgical settings.

    To view Dr. Graham Copeland's publications, visit PubMed

    Content Contributors
    • Jennie Kim, MD
    About the Creator
    Dr. Graham Copeland
    Content Contributors
    • Jennie Kim, MD