BISAP Score Calculator

BISAP Score Calculator for Gastroenterology. Scores of 0 to 2 identify a lower-risk group with in-hospital mortality under roughly 2 percent, supporting routine ward management. Scores of 3 to 5 mark a high-risk group where mortality rises steeply, exceeding 20 percent at a score of 5 in the derivation data. The commonly used cutoff of a score of 3 or greater is where risk of organ failure, persistent organ failure, and pancreatic necrosis climbs sharply, and it is a practical threshold for escalating monitoring intensity. The score is meant to drive disposition and vigilance decisions early rather than to make a fixed prognosis.

How this calculator works

The Bedside Index for Severity in Acute Pancreatitis (BISAP) assigns one point each for five variables measured within the first 24 hours of admission: blood urea nitrogen above 25 mg/dL, impaired mental status (any acute alteration in consciousness/GCS below 15), presence of the systemic inflammatory response syndrome (SIRS), age over 60 years, and imaging evidence of a pleural effusion. The five points are summed for a total of 0 to 5, so the mnemonic is literally B-I-S-A-P. It was derived by Classification and Regression Tree analysis on nearly 18,000 US admissions to predict in-hospital mortality, and it deliberately uses only routinely available bedside data so it can be computed without CT scoring or 24-hour observation windows.

When to use this calculator

Use BISAP as an early triage tool at or near admission for any adult with acute pancreatitis, once the diagnosis is established, to flag who needs closer monitoring or an ICU-level bed. Its main advantage over Ranson and APACHE II is that it is complete within 24 hours and needs no serial 48-hour labs or contrast CT. It is not a diagnostic test for pancreatitis, is not validated in children, and should not replace organ-failure assessment: a low score in a patient with evolving hypotension, hypoxia, or rising creatinine does not override clinical deterioration.

Inputs used

  • Blood urea nitrogen
  • Mental status
  • SIRS criteria
  • Age
  • Pleural effusion

Clinical interpretation

Scores of 0 to 2 identify a lower-risk group with in-hospital mortality under roughly 2 percent, supporting routine ward management. Scores of 3 to 5 mark a high-risk group where mortality rises steeply, exceeding 20 percent at a score of 5 in the derivation data. The commonly used cutoff of a score of 3 or greater is where risk of organ failure, persistent organ failure, and pancreatic necrosis climbs sharply, and it is a practical threshold for escalating monitoring intensity. The score is meant to drive disposition and vigilance decisions early rather than to make a fixed prognosis.

Worked example

Consider a 68-year-old man admitted with gallstone pancreatitis: BUN 32 mg/dL (+1), alert and oriented (0), respiratory rate 24 and heart rate 104 meeting two SIRS criteria (+1), age 68 (+1), and a small left pleural effusion on chest imaging (+1). His BISAP score is 4. A score in the 3 to 5 range corresponds to roughly 5 to 20 percent in-hospital mortality and, in the prospective cohort, a score of 3 or higher carried about a 7-fold increased odds of organ failure. This patient warrants intensive monitoring, aggressive early resuscitation, and consideration of an ICU or step-down bed.

Limitations and safety notes

BISAP predicts mortality well (AUC around 0.82) but is only modestly discriminating for severity subtypes such as necrosis, and its overall accuracy is comparable to, not clearly better than, APACHE II. Because SIRS and BUN are transient, a single 24-hour snapshot can misclassify patients whose course changes; it should be interpreted alongside trended labs and organ-function measures. The pleural effusion criterion depends on chest imaging being obtained, and impaired mental status can be confounded by intoxication, sedation, or dementia rather than pancreatitis severity itself.

Frequently asked questions

What is the BISAP cutoff that defines high risk?

A score of 3 or higher is the standard threshold for high risk. At that level, in-hospital mortality rises substantially and the odds of developing organ failure, persistent organ failure, and pancreatic necrosis increase several-fold, so it is a reasonable trigger for intensive monitoring or ICU consideration.

How is BISAP different from Ranson's criteria?

BISAP uses only five variables and is complete within the first 24 hours, whereas Ranson's criteria require data at admission and again at 48 hours. BISAP therefore gives an actionable early estimate rather than requiring a two-day observation window, while offering broadly similar predictive accuracy for mortality.

Does a low BISAP score mean the patient will do well?

Not necessarily. BISAP is a probabilistic early-triage tool, not a guarantee. A patient with a score of 0 to 2 who develops hypotension, hypoxia, or rising creatinine should be treated as severe regardless of the initial score, since the value reflects only the first-24-hour snapshot.

Which SIRS definition does BISAP use?

BISAP counts SIRS as present when at least two of the standard four criteria are met: temperature below 36 or above 38 degrees C, heart rate over 90, respiratory rate over 20 (or PaCO2 under 32 mmHg), and white cell count below 4 or above 12 x10^9/L (or over 10 percent bands).

References

  • Wu BU, Johannes RS, Sun X, Tabak Y, Conwell DL, Banks PA. The early prediction of mortality in acute pancreatitis: a large population-based study. Gut. 2008. PMID: 18519429.
  • Singh VK, Wu BU, Bollen TL, Repas K, Maurer R, Johannes RS, Mortele KJ, Conwell DL, Banks PA. A prospective evaluation of the bedside index for severity in acute pancreatitis score in assessing mortality and intermediate markers of severity in acute pancreatitis. Am J Gastroenterol. 2009. PMID: 19293787.
  • Tenner S, Baillie J, DeWitt J, Vege SS. American College of Gastroenterology guideline: management of acute pancreatitis. Am J Gastroenterol. 2013. PMID: 23896955.

Editorial review and citation methodology

Reviewed by the Quick Medical Calculator Editorial Team. Last reviewed: April 17, 2026. The review checks calculator inputs, intended population, interpretation, limitations, and source alignment.

  • Prefer original validation studies for scoring systems and prediction tools.
  • Use current specialty society guidance, transplant allocation policy, public health guidance, or regulator resources when they govern clinical use.
  • Include limitations and safety notes when a calculator is population-specific, context-dependent, or unsuitable as a standalone decision tool.

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