BISAP Score Calculator
BISAP score for acute pancreatitis from five bedside criteria, with lower and higher risk groups.
What it does
BISAP stands for bedside index for severity in acute pancreatitis. It was designed to identify patients at higher risk of severe disease within the first 24 hours of presentation.
The score uses five items: blood urea nitrogen above 25 mg/dL, impaired mental status, evidence of systemic inflammatory response syndrome, age above 60 years, and pleural effusion on imaging. Each item adds 1 point.
A score of 0 to 2 is the lower-risk group. A score of 3 to 5 is the higher-risk group and is associated with more severe disease in validation studies. BISAP is simple enough for the bedside, but it does not replace early fluid assessment, imaging, or organ failure scoring.
The defaults show a BUN of 18 mg/dL, normal mental status, SIRS present, age 52, and no pleural effusion. Only SIRS is positive, so the score is 1 and the patient falls in the lower-risk group.
How to use
- Choose BUN in mg/dL or urea in mmol/L, depending on the laboratory report.
- Enter the BUN or urea value from the first 24 hours of admission.
- Select whether mental status is normal or impaired.
- Indicate whether SIRS is present, meaning two or more SIRS criteria.
- Enter age and select whether a pleural effusion is present on imaging.
- Press Calculate to see the total score and the lower or higher risk group.
Formula
- BUN
- 1 point when above 25 mg/dL. Urea in mmol/L is multiplied by 2.8.
- Mental status
- 1 point for impaired mental status.
- SIRS
- 1 point when two or more SIRS criteria are present.
- Age
- 1 point when older than 60 years.
- Pleural effusion
- 1 point when present on imaging.
Each of the five items contributes 1 point. Urea in mmol/L is converted to BUN in mg/dL with a factor of 2.8, so 6.4 mmol/L is about 18 mg/dL. The score was derived for the first 24 hours of acute pancreatitis. A score of 3 or more is the higher-risk group in validation work; the score does not provide a precise mortality estimate for an individual patient.
Worked example
Example: BUN 18, normal mental status, SIRS present, age 52
Defaults: BUN 18 mg/dL, normal mental status, SIRS present, age 52, no pleural effusion.
- BUN 18 mg/dL is not above 25: 0 points.
- Mental status is normal: 0 points.
- SIRS is present: 1 point.
- Age 52 is not above 60: 0 points.
- No pleural effusion: 0 points.
- Total is 1 of 5, which is in the lower-risk group (0 to 2).
- The tool suggests continued supportive care and reassessment.
Reference table
| Item | Point | Positive when |
|---|---|---|
| BUN | 1 | Above 25 mg/dL |
| Mental status | 1 | Impaired |
| SIRS | 1 | Two or more criteria |
| Age | 1 | Above 60 years |
| Pleural effusion | 1 | Present on imaging |
Limits
- BISAP was designed for the first 24 hours of acute pancreatitis and is not a late severity score.
- It does not replace organ failure assessment, imaging, or the full clinical picture.
- A lower score does not guarantee a mild course, and a higher score does not confirm severe disease.
- The score does not provide an individual mortality prediction.
Common mistakes
- Entering urea in mmol/L without selecting the urea unit.
- Counting BUN of exactly 25 mg/dL as positive when the threshold is above 25.
- Counting age 60 as positive when the threshold is above 60.
- Selecting SIRS without confirming at least two SIRS criteria.
- Using BISAP as a stand-alone discharge or intensive care decision tool.
Try it yourself
Quick checks. Answers sit tucked under each question.
A patient has BUN 30 mg/dL, impaired mental status, SIRS, age 70, and a pleural effusion. What is the score?
5 of 5. Every item is positive, which is in the higher-risk group.
A patient has BUN 12 mg/dL, normal mental status, no SIRS, age 45, and no effusion. What is the score?
0 of 5. No item is positive, which is in the lower-risk group.
A patient has BUN 28 mg/dL, normal mental status, SIRS, age 66, and no effusion. What is the score?
3 of 5. BUN, SIRS, and age are positive, which is in the higher-risk group.
Questions
What does BISAP stand for?
Bedside index for severity in acute pancreatitis. It is a five-item score used early in admission.
What BISAP score is severe?
A score of 3 or more is the higher-risk group in validation studies. It does not define severe pancreatitis by itself.
Why does BISAP use BUN rather than creatinine?
BUN rises early with dehydration and is part of the original bedside index. It reflects both renal function and volume status.
Does BISAP need imaging?
Only the pleural effusion item needs imaging. The other four items are clinical or laboratory values available at the bedside.
Can BISAP be used after 24 hours?
It was derived for the first 24 hours. Later scores may not carry the same meaning, and other tools may be more appropriate.
Does a BISAP of 0 mean the patient can go home?
No. Disposition depends on pain control, oral intake, organ function, imaging, and the full clinical course.
Sources
- Wu et al., BISAP derivation in acute pancreatitis
- BISAP validation and severity review
- BISAP original article DOI