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BISAP Score Calculator (Acute Pancreatitis)

Bedside Index of Severity in Acute Pancreatitis (BISAP) — BUN, impaired mental status, SIRS, age over 60 and pleural effusion in the first 24 hours — with in-hospital mortality by score.

BUN > 25 mg/dL (urea nitrogen > 8.9 mmol/L)

Impaired mental status (Glasgow Coma Scale < 15)

SIRS — 2 or more criteria present

Age > 60 years

Pleural effusion on imaging

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How it works

BISAP = 1 point each for BUN > 25 mg/dL, impaired mental status, SIRS, age > 60 and pleural effusion, assessed within 24 hours of presentation; range 0–5. Score ≥ 3 = increased mortality and risk of organ failure.

BISAP was derived by Wu and colleagues (2008) from more than 17,000 admissions to predict in-hospital death from acute pancreatitis using five items available on day one. It is simpler than Ranson’s criteria (which need 48 hours) or APACHE II. Mortality rose from under 1% at a score of 0–1 to over 20% at a score of 5 in the derivation and validation cohorts; a score of 3 or more also predicts persistent organ failure and pancreatic necrosis. Treat the figures as population averages, not individual predictions.

Worked example

A 68-year-old with BUN 32 mg/dL, normal mental status, no SIRS and no pleural effusion: BUN 1 + age 1 = 2 / 5 — low-risk group, with in-hospital mortality of about 1.9–2.1% in the original cohorts.

Sources: Wu BU et al. The early prediction of mortality in acute pancreatitis: a large population-based study. Gut 2008

Frequently asked questions

What BISAP score is severe pancreatitis?

A score of 3 or more marks a higher-risk group, with mortality of roughly 5–8% at 3 and above 20% at 5 in the original study, and higher rates of organ failure.

When should BISAP be calculated?

Within the first 24 hours of hospital presentation, using the worst values in that period.

How is BISAP different from Ranson’s criteria?

Ranson uses 11 items over 48 hours; BISAP uses five items available on day one, so it can guide early triage. Both perform similarly for predicting death.

How do I convert urea to BUN?

BUN (mg/dL) = urea (mmol/L) × 2.8. The threshold of 25 mg/dL corresponds to about 8.9 mmol/L of urea nitrogen.

Related calculators

Ranson Criteria Calculator (Acute Pancreatitis)

Ranson score for acute pancreatitis severity — five admission criteria and six 48-hour criteria for non-gallstone and gallstone pancreatitis — with predicted mortality.

SIRS Criteria Calculator

Count the 4 SIRS criteria (temperature, heart rate, respiratory rate or PaCO₂, white cell count or bands) in °C or °F, then check sepsis, severe sepsis and septic shock with the SEP-1 organ-dysfunction list, plus qSOFA and the Sepsis-3 shock criteria.

Glasgow Coma Scale (GCS) Calculator

Add the eye, verbal and motor responses into a Glasgow Coma Scale total from 3 to 15 and read the mild, moderate or severe impairment band.

Rockall Score Calculator (Upper GI Bleeding)

Rockall score for acute upper gastrointestinal bleeding — age, shock, comorbidity, endoscopic diagnosis and stigmata of recent haemorrhage — pre-endoscopy and complete score with mortality.

Clinical decision tool for education and for use by trained clinicians alongside clinical judgement — not a diagnosis and not a substitute for medical assessment. Scores validated in specific populations may not apply to every patient.