Mannheim Peritonitis Index (MPI)
Mortality risk in secondary peritonitis, scored at laparotomy
Sources last checked: 2026-10-13
Mannheim Peritonitis Index (MPI)
Mortality risk in secondary peritonitis, scored at laparotomy
Requires intraoperative findings, so it is a postoperative prognostic tool, not a decision aid for whether to operate. Mortality varied widely between centres (0–11 % in the lowest band).
Interpretation
| < 21 | Mean mortality 2.3 % in the 2003-patient European validation. |
|---|---|
| 21–29 | Mean mortality 22.5 %. |
| > 29 | Mean mortality 59.1 %. |
What is the Mannheim Peritonitis Index (MPI)?
The Mannheim Peritonitis Index scores eight risk factors — age, sex, organ failure, malignancy, duration of peritonitis, origin of sepsis, extent and type of exudate — to estimate mortality in secondary peritonitis. Linder, Wacha and colleagues developed it in Mannheim, Germany, in 1987. Billing et al. validated it in 2 003 patients from seven centres in three European countries.
When to use it
- Prognostic assessment at laparotomy for secondary peritonitis
- Mortality-risk stratification in secondary peritonitis
- Comparing peritonitis cohorts in audit and research
When not to use it
- Primary (spontaneous bacterial) or dialysis-associated peritonitis
- Before surgery, because several items need intraoperative findings
How it is calculated
| Criterion | Points |
|---|---|
| Age > 50 years | +5 |
| Female sex | +5 |
| Organ failure | +7 |
| Malignancy | +4 |
| Preoperative duration of peritonitis > 24 h | +4 |
| Origin of sepsis not colonic | +4 |
| Diffuse generalised peritonitis | +6 |
| Exudate | |
| Clear | 0 |
| Cloudy / purulent | 6 |
| Faecal | 12 |
Clinical pearls and limitations
- Requires intraoperative findings, so it is a postoperative prognostic tool, not a decision aid for whether to operate. Mortality varied widely between centres (0–11 % in the lowest band).
- A score above 26 is the commonly quoted threshold for high mortality risk (sensitivity 86 %, specificity 74 % in Billing's data).
- Faecal exudate alone adds 12 points — nearly a third of the maximum.
- Organ failure items include intestinal obstruction (paralysis > 24 h or complete mechanical ileus), not only renal, pulmonary and circulatory failure.
Frequently asked questions
What is a high Mannheim Peritonitis Index?
Above 29 (mean mortality ≈ 59 %); 21–29 is intermediate (≈ 22 %). A threshold of 26 is often used to predict death.
What is the maximum MPI score?
47 points.
Why does female sex add points?
Female sex was weighted as an independent risk factor in the derivation data, so the index carries it; it is an empirical weight, not a causal explanation.
Evidence and guidelines
- Primary source: Linder MM, Wacha H, Feldmann U, Wesch G, Streifensand RA, Gundlach E. Der Mannheimer Peritonitis-Index. Ein Instrument zur intraoperativen Prognose der Peritonitis. Chirurg 1987;58(2):84-92. Weights as tabulated in open-access validations (e.g. PMC12121696; maximum 47).
- Billing A, Fröhlich D, Schildberg FW. Prediction of outcome using the Mannheim peritonitis index in 2003 patients. Br J Surg 1994;81(2):209-213 (seven centres in three European countries; source of the bands; threshold 26: sensitivity 86 %, specificity 74 %).
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