MAGENT

BISAP score: how the five points for acute pancreatitis are counted

The BISAP score gives 1 point for each of five findings in acute pancreatitis: BUN over 25 mg/dL, Impaired mental status, SIRS, Age over 60 and Pleural effusion. The total runs from 0 to 5.

Not a medical device. Not a diagnosis or dosing recommendation.

Use this calculator via API

What is the BISAP score?

BISAP stands for bedside index for severity in acute pancreatitis. It comes from Bechien Wu and colleagues, who described it in Gut in 2008. Their abstract says they used Classification and Regression Tree analysis to find five variables for predicting in-hospital mortality, with one point for each one present early in the illness, within the first day.

Magent's calculator is the Wu 2008 BISAP score. It isn't Ranson's criteria, APACHE II or the CT severity index (CTSI).

This page explains the arithmetic. The calculator returns the total out of 5. It doesn't return mortality percentages, and this page doesn't say what a total means for a particular person.

The BISAP formula

BISAP = BUN over 25 mg/dL (1)
      + impaired mental status (1)
      + SIRS (1)
      + age over 60 (1)
      + pleural effusion (1)
maximum = 5

Exact expression the calculator uses:

BISAP = (bun_mg_dl>25) + impaired_mental_status + sirs + (age>60) + pleural_effusion; each 1 if present; max 5

What each item means

InputScores 1 point when
bun_mg_dlBlood urea nitrogen is over 25 mg/dL (the calculator takes 1 to 200)
impaired_mental_statusYou mark mental status as impaired (the paper counted any recorded disorientation, lethargy, somnolence, coma or stupor)
sirsYou mark SIRS as present
ageAge is over 60 (the calculator takes 18 to 120)
pleural_effusionYou mark a pleural effusion as present, from imaging

How the score works

  1. Score BUN. Over 25 mg/dL is 1 point. Exactly 25.0 is 0.
  2. Score age. Over 60 is 1 point. Exactly 60 is 0.
  3. Mark the three flags. Impaired mental status, SIRS and pleural effusion are true or false. True is 1 point.
  4. Add them up. The total is 0 to 5.

Inputs come from the user

Three of the five items are flags that the person using the calculator sets. Magent's calculator doesn't take a GCS or judge mental status, doesn't work out SIRS from vital signs, and doesn't read imaging. It scores BUN and age from the numbers you enter. It returns the total, the maximum of 5, the age and BUN it used and a line for each item.

Worked examples

These use Magent's own expected values for the calculator. Each line adds the items in BISAP order: BUN, mental status, SIRS, age, pleural effusion.

Example 1: age 50, BUN 20, no flags

  1. BUN 20 isn't over 25 → 0. Age 50 isn't over 60 → 0.
  2. Score: 0 + 0 + 0 + 0 + 0 = 0 out of 5.

Example 2: Example 1 with BUN 25.0

  1. BUN 25.0 isn't over 25 → 0.
  2. Score: 0 + 0 + 0 + 0 + 0 = 0 out of 5.

Example 3: Example 1 with BUN 26

  1. BUN 26 is over 25 → 1.
  2. Score: 1 + 0 + 0 + 0 + 0 = 1 out of 5.

Example 4: Example 1 at age 60

  1. Age 60 isn't over 60 → 0.
  2. Score: 0 + 0 + 0 + 0 + 0 = 0 out of 5.

Example 5: Example 1 at age 61

  1. Age 61 is over 60 → 1.
  2. Score: 0 + 0 + 0 + 1 + 0 = 1 out of 5.

Example 6: age 61, BUN 26, all three flags

  1. BUN 26 → 1. Age 61 → 1. Each flag → 1.
  2. Score: 1 + 1 + 1 + 1 + 1 = 5 out of 5, the maximum.

History of the BISAP score

The score comes from Wu BU, Johannes RS, Sun X, Tabak Y, Conwell DL and Banks PA, The early prediction of mortality in acute pancreatitis: a large population-based study, Gut, 2008 (volume 57, issue 12, pages 1698–1703). The abstract describes a scoring system for predicting in-hospital mortality, built with Classification and Regression Tree analysis and then checked against APACHE II in a separate group of cases.

Singh and colleagues reported a prospective evaluation of the score in the American Journal of Gastroenterology in 2009.

Papachristou and colleagues compared BISAP with Ranson's criteria, APACHE-II and CTSI in the American Journal of Gastroenterology in 2010.

When it's used

The 2008 paper scored findings from the first day of acute pancreatitis. The 2012 revision of the Atlanta classification (published 2013) and the 2024 American College of Gastroenterology guideline on acute pancreatitis are listed under Further reading.

Where it's used

The inputs come from a blood test, the person's age, a bedside check of mental status and vital signs, and imaging.

Who uses it

The person using the calculator sets the three flags. The calculator scores BUN and age and adds the points.

Limits of the calculation

  • It adds up five items. It doesn't confirm acute pancreatitis or set its severity.
  • Mental status, SIRS and pleural effusion are flags you set. The calculator doesn't take a GCS, recompute SIRS or read imaging.
  • BUN over 25 and age over 60 are strict: 25.0 and 60 don't score.
  • It returns a score, not a mortality percentage.
  • It isn't Ranson's criteria, APACHE II or CTSI.

Clinical decisions belong to a qualified clinician who knows the patient.

  • SIRS criteria count vital-sign and white cell findings. BISAP takes SIRS as a single yes/no item.
  • Ranson's criteria, APACHE II and CTSI are separate scores with their own inputs.

Glossary

  • BUN: blood urea nitrogen, a blood test of urea.
  • SIRS: systemic inflammatory response syndrome, defined by vital-sign and white cell criteria.
  • GCS: Glasgow Coma Scale, a scale of consciousness.
  • Pleural effusion: fluid around the lung, seen on imaging.
  • Acute pancreatitis: sudden inflammation of the pancreas.

Common mistakes

  • Scoring BUN of exactly 25. It has to be over 25.
  • Scoring age 60. It has to be over 60.
  • Entering BUN in mmol/L. The calculator takes mg/dL.
  • Expecting a mortality percentage. The calculator returns the score.

Source

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;57(12):1698-1703. DOI: 10.1136/gut.2008.152702. PMID: 18519429

Further reading

  1. Singh VK, et al. 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;104(4):966-971. PMID: 19293787
  2. Papachristou GI, et al. Comparison of BISAP, Ranson's, APACHE-II, and CTSI scores in predicting organ failure, complications, and mortality in acute pancreatitis. Am J Gastroenterol. 2010;105(2):435-441. PMID: 19861954
  3. Banks PA, et al. Classification of acute pancreatitis--2012: revision of the Atlanta classification and definitions by international consensus. Gut. 2013;62(1):102-111. PMID: 23100216
  4. Tenner S, et al. American College of Gastroenterology Guidelines: Management of Acute Pancreatitis. Am J Gastroenterol. 2024;119(3):419-437. PMID: 38857482

Frequently asked questions

How do you calculate the BISAP score?

Give 1 point each for BUN over 25 mg/dL, impaired mental status, SIRS, age over 60 and pleural effusion. Add them up for a total from 0 to 5.

What does BISAP stand for?

Bedside index for severity in acute pancreatitis. The letters also match the five items: BUN, impaired mental status, SIRS, age and pleural effusion.

What is the highest BISAP score?

5, when all five items are present.

Does a BUN of 25 count?

No. BUN has to be over 25 mg/dL.

Does the calculator give a mortality percentage?

No. It returns the score out of 5.