How do you assess the severity of acute pancreatitis?

Assessing Disease Severity in Acute Pancreatitis

All patients with acute pancreatitis should undergo severity stratification within 48 hours using the BISAP score (within 24 hours) combined with C-reactive protein measurement, followed by contrast-enhanced CT scanning between days 3-10 for those predicted to have severe disease. 1

Initial Assessment (Within 24 Hours)

BISAP Score - Primary Recommended Tool

Calculate the BISAP score immediately upon admission as it is the simplest and most accurate bedside tool for early risk stratification. 1 The BISAP score evaluates five parameters:

• Blood urea nitrogen >25 mg/dL
• Impaired mental status
• Systemic inflammatory response syndrome (SIRS)
• Age >60 years
• Pleural effusion on imaging 1

A BISAP score ≥2 indicates severe acute pancreatitis with increased risk of organ failure and mortality (AUC 0.80 for severe pancreatitis, 0.93 for organ failure). 1 The key advantage is identifying high-risk patients before organ failure develops. 1

Alternative: APACHE II Score

If BISAP is equivocal or for ongoing monitoring, use APACHE II scoring. 1 An APACHE II score ≥8 indicates severe disease, while a score ≥6 has 95% sensitivity for detecting complications (though only 50% positive predictive value). 2, 1 APACHE II is more cumbersome but provides the highest accuracy (AUC 0.88) and should be calculated daily in severe cases to monitor disease progression, recovery, or onset of sepsis. 2, 1

Assessment at 48 Hours

Glasgow Score

Three or more positive Glasgow criteria over 48 hours constitutes severe disease with 70-80% accuracy. 2, 3 The Glasgow score has been validated in UK populations and includes parameters such as age, white blood cell count, glucose, urea, PaO2, calcium, albumin, and LDH. 2

C-Reactive Protein (CRP)

CRP is the most valuable single laboratory marker for severity prediction. 3 Measure CRP levels with the following thresholds:

• Peak CRP >210 mg/L in the first 4 days indicates severe disease with ~80% accuracy 2, 1
• CRP >120 mg/L at the end of the first week indicates severe disease 2
• CRP ≥150 mg/L on day 3 is the preferred cutoff for predicting severe acute pancreatitis 1, 4

Combining CRP with Glasgow criteria further improves prognostication. 2, 3

Ranson Score

If BISAP is unavailable, Ranson score ≥3 indicates severe disease (sensitivity 75-87%, specificity 68-77.5%). 1, 3 However, this requires 48 hours to complete and is less practical than BISAP. 1

Additional Critical Laboratory Markers

Monitor these independent predictors of poor outcomes:

• Hematocrit >44% - independent risk factor for pancreatic necrosis 1, 4
• Blood urea nitrogen >20 mg/dL - independent predictor of mortality 1, 4
• Procalcitonin - most sensitive for detecting pancreatic infection; low values strongly predict absence of infected necrosis 1, 4

Radiological Assessment (Days 3-10)

Contrast-Enhanced CT with CT Severity Index (CTSI)

All patients with predicted severe disease by clinical scoring should undergo dynamic contrast-enhanced CT between 3-10 days after admission. 2, 1, 3 Timing is critical:

• Avoid CT before 72 hours as it underestimates pancreatic necrosis 4
• Perform after initial resuscitation is complete 2

The CTSI combines pancreatic inflammation grade and extent of necrosis, scoring 0-10. 1 CTSI is the most reliable radiological predictor of infected necrosis and complications requiring surgical intervention. 2

• CTSI 0-1: minimal morbidity and mortality
• CTSI 7-10: 92% morbidity, 17% mortality 1
• CTSI ≥3: indicates severe disease 1

The CTSI has pooled AUC of 0.80 for severity and 0.79 for mortality prediction. 5

Clinical Assessment of Organ Failure

The presence of organ failure (pulmonary, circulatory, or renal insufficiency) clinically defines a severe attack per Atlanta criteria. 1, 3 Monitor continuously as organ failure is the primary driver of mortality. 3

Practical Algorithmic Approach

Hour 0-24:

• Calculate BISAP score immediately 1
• Measure baseline CRP 1
• Assess for clinical organ failure 1, 3
• Check hematocrit and BUN 1, 4

Hour 48:

• Recalculate Glasgow score (if ≥3 positive criteria = severe) 2, 3
• Measure CRP (target day 3 for ≥150 mg/L threshold) 1, 4
• Calculate APACHE II if BISAP equivocal 1
• Begin daily APACHE II monitoring in severe cases 2, 1

Days 3-10:

• Perform contrast-enhanced CT with CTSI calculation in all patients with BISAP ≥2, APACHE II ≥8, Glasgow ≥3, or clinical organ failure 2, 1, 3
• Assess extent of pancreatic necrosis and peripancreatic fluid collections 2, 1

Common Pitfalls to Avoid

Clinical assessment alone misclassifies approximately 50% of patients - always use objective scoring systems. 3 Do not rely on single measurements; severity can evolve rapidly in the first 48-72 hours. 2 Avoid early CT scanning (<72 hours) unless diagnostic uncertainty exists, as it underestimates necrosis extent. 4 While APACHE II has the highest accuracy for mortality prediction (AUC 0.91), its complexity limits bedside utility compared to BISAP. 1, 5