POSSUM (operative morbidity & mortality)
POSSUM — Physiological and Operative Severity Score: 12 physiological + 6 operative variables (each graded 1/2/4/8) drive logistic equations for predicted 30-day morbidity and mortality.
Open the calculator → Runs in your browser. Data leaves only if you deliberately send a problem report from the interactive tool.
Example
- Age
- 4
- Cardiac status
- 2
- Respiratory status
- 2
- Systolic blood pressure
- 2
- Pulse
- 4
- Glasgow Coma Score
- 1
- Hemoglobin
- 4
- White-cell count
- 2
- Urea
- 4
- Sodium
- 2
The other 8 values
- Potassium
- 1
- ECG
- 4
- Operative severity
- 4
- Number of procedures
- 1
- Blood loss
- 4
- Peritoneal soiling
- 4
- Malignancy
- 1
- Urgency
- 4
Result: POSSUM physiological score 32, operative score 18: predicted 30-day morbidity 93.3%, mortality 50%.
The tool opens with these values already filled in. Replace them with your own.
What the result means
- Scores
- physiological score 12–88 (12 variables) + operative score 6–48 (6 variables), each graded 1/2/4/8.
- Equations
- morbidity ln[R/(1−R)] = −5.91 + 0.16·phys + 0.19·op; mortality ln[R/(1−R)] = −7.04 + 0.13·phys + 0.16·op. POSSUM over-predicts mortality at the low end — see P-POSSUM.
What you enter
- Age (point grade)
- Cardiac status (point grade)
- Respiratory status (point grade)
- Systolic blood pressure (point grade)
- Pulse (point grade)
- Glasgow Coma Score (point grade)
- Hemoglobin (point grade)
- White-cell count (point grade)
- Urea (point grade)
- Sodium (point grade)
The other 8 fields
- Potassium (point grade)
- ECG (point grade)
- Operative severity (point grade)
- Number of procedures (point grade)
- Blood loss (point grade)
- Peritoneal soiling (point grade)
- Malignancy (point grade)
- Urgency (point grade)
How this is calculated
Copeland GP, Jones D, Walters M. POSSUM: a scoring system for surgical audit. Br J Surg. 1991;78(3):355-360. Read the source ↗
A reference and educational tool. Not medical, legal, or financial advice, and not a substitute for clinician judgment.