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BISAP Score

BISAP Score — Acute Pancreatitis

5-variable severity score for acute pancreatitis (AUC 0.82). Assessed within 24h of admission — no 48h wait required. Score ≥ 3 = ICU-level care.

Within 24 Hours of Presentation

Guidelines & Evidence

Clinical Details

Section 1

When to Use

Rapid bedside risk stratification of patients with acute pancreatitis (within first 24 hours)

To predict in-hospital mortality and severe acute pancreatitis (SAP)

Early triage to identify patients requiring aggressive fluid resuscitation or ICU monitoring

To provide prognostic information to family and multidisciplinary teams early in the admission

Patient Population

Adults with acute pancreatitis. Validated in multiple large-scale observational studies and compared head-to-head with Ranson and APACHE II.

When to Use APACHE II or Marshall Instead

Beyond 24 hours — the score is primarily a "snapshot" early predictor; persistent organ failure (Marshall/SOFA) is better for monitoring progress

Predicting infected necrosis — BISAP is better at predicting mortality than local complications

ICU research trials — APACHE II remains the standard for rigorous study matching

Section 2

Formula & Logic

The BISAP Acronym (5 Points)

B (BUN): > 25 mg/dL (8.9 mmol/L). Reflects under-resuscitation or renal compromise.

I (Impaired Mental Status): Disorientation, lethargy, or GCS < 15.

S (SIRS): Presence of 2 or more SIRS criteria (Temp, HR, RR, WBC).

A (Age): > 60 years.

P (Pleural Effusion): Identified within the first 24 hours (via chest X-ray, ultrasound, or CT).

Mortality Risk Stratification

0–2 Points	Low Risk (< 2% mortality)
3 Points	Moderate Risk (~5–8% mortality)
4 Points	High Risk (~12–15% mortality)
5 Points	Very High Risk (> 22% mortality)

Section 3

Pearls/Pitfalls

Simplicity vs. Accuracy

The BISAP score is significantly simpler to calculate than Ranson or APACHE II, requiring only five bedside variables. Despite this, its discrimination (C-index ~0.82) for predicting in-hospital mortality is comparable to more complex ICU scoring systems.

The Importance of SIRS

Persistent SIRS (Systemic Inflammatory Response Syndrome) for more than 48 hours is a separate and powerful marker of persistent organ failure. BISAP captures the early "snapshot" of this inflammatory surge.

Clinical Pearls

BISAP ≥ 3 is the standard threshold for "Severe" disease

Early identification of pleural effusion (the "P" in BISAP) is a strong surrogate for systemic vascular leak

BUN elevation is a particularly sensitive marker of "fluid-unresponsive" disease and mortality

Section 4

Next Steps

Management Action

BISAP 0-2: Ward management with standard crystalloid resuscitation.

BISAP ≥ 3: High priority for ICU/Step-down. Consider pulse-oximetry and aggressive fluid monitoring. Early enteral nutrition.

Complementary Tools

APACHE II Score

Ranson Criteria

Marshall Score (Organ Failure)

MCTSI (CT Severity)

Section 5

Evidence Appraisal

Original Derivation

The early prediction of mortality in acute pancreatitis: a large-cost-effective prognostic tool (BISAP).

Wu BU et al. • Gut. 2008;57(12):1698-703. Derived from 17,992 cases.

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Comparative Validation

Comparison of BISAP with Ranson's, APACHE-II, and CTSI in predicting mortality.

Papachristou GI et al. • American Journal of Gastroenterology. 2010;105(2):435-41. Independent head-to-head comparison.

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Section 6

Literature

Bedside Index Philosophy

Developed by Dr. Bechien Wu and colleagues. The goal was to provide a score that clinicians could calculate "on the fly" in the Emergency Department without waiting for 48 hours (like Ranson) or calculating 12 variables (like APACHE II).

Last Comprehensive Review: 2026

Related Gastroenterology Tools

Glasgow-Blatchford Score

AIMS65 Score

Forrest Classification

Rockall Score