What are the Ranson criteria for alcoholic and biliary acute pancreatitis, and how does the total score predict severity, mortality risk, and guide management?

Ranson Score for Acute Pancreatitis

What is the Ranson Score?

The Ranson score is an 11-parameter scoring system calculated over 48 hours (5 criteria at admission, 6 at 48 hours) that predicts severity in acute pancreatitis, with ≥3 points indicating severe disease. 1, 2

• The score achieves 75-87% sensitivity and 68-77.5% specificity for predicting severe acute pancreatitis. 1, 2
• However, the positive predictive value is only 28.6-49%, meaning many patients classified as severe will recover uneventfully. 1, 2

Ranson Criteria Components

At admission (0 hours):

• Age >55 years 3, 4
• White blood cell count >16,000/mm³ 3, 4
• Blood glucose >200 mg/dL 3, 4
• Serum lactate dehydrogenase >350 IU/L 3, 4
• Aspartate aminotransferase >250 IU/L 3, 4

At 48 hours:

• Hematocrit fall >10% 3, 4
• Blood urea nitrogen rise >5 mg/dL 3, 4
• Serum calcium <8 mg/dL 3, 4
• Arterial PO₂ <60 mmHg 3, 4
• Base deficit >4 mEq/L 3, 4
• Fluid sequestration >6 liters 3, 4

Mortality and Severity Prediction

Ranson score ≥3 defines severe acute pancreatitis and correlates with increased mortality risk. 1, 2

• In severe acute pancreatitis patients, non-survivors had significantly higher Ranson scores (5.6 ± 0.5) compared to survivors (3.4 ± 0.2). 3
• The 48-hour Ranson variables (particularly BUN, calcium, base deficit, and fluid sequestration) predict mortality more accurately than admission variables. 3
• Overall mortality in acute pancreatitis ranges from 3.2% in general populations to 21% in severe cases requiring ICU admission. 3, 4

Critical Limitations of Ranson Score

The major disadvantage of Ranson scoring is the mandatory 48-hour delay before complete assessment, which prevents early risk stratification and timely intervention. 1, 2, 4

• Clinical assessment alone misclassifies approximately 50% of patients, yet waiting 48 hours for Ranson completion can result in potentially avoidable deaths. 5
• The score does not reliably predict the extent of pancreatic necrosis, requiring CT imaging for accurate assessment. 2, 5
• All traditional 48-hour scores (Ranson, Glasgow) can only be assessed after 48 hours and thus do not enable risk stratification on admission. 1

Recommended Alternative: BISAP Score

Current guidelines from the World Journal of Emergency Surgery and American College of Surgeons recommend using the BISAP score instead of Ranson because it can be calculated within 24 hours with equivalent or superior accuracy. 2, 6

• BISAP score ≥2 is the critical cutoff for severe acute pancreatitis, with area under the curve of 0.80 for severe disease and 0.93 for organ failure. 2, 6
• BISAP identifies patients at increased risk of mortality before the onset of organ failure, unlike Ranson. 1, 6
• BISAP predicts severity, death, and organ failure as well as APACHE-II and better than Ranson criteria. 1

BISAP components (one point each):

• Blood urea nitrogen >25 mg/dL 2, 6
• Impaired mental status 2, 6
• Systemic inflammatory response syndrome present 2, 6
• Age >60 years 2, 6
• Pleural effusion on radiography 2, 6

Practical Clinical Algorithm

Within first 24 hours:

• Calculate BISAP score immediately upon admission. 2, 6
• Obtain baseline labs including CRP, hematocrit, and BUN. 6, 5
• Assess clinically for organ failure (respiratory, circulatory, or renal), which definitively indicates severe disease regardless of any score. 2, 6, 5

At 48 hours (if needed for equivocal cases):

• Calculate Ranson score only if BISAP is borderline or clinical picture remains unclear. 6, 5
• Alternatively, use APACHE-II score (≥8 indicates severe disease) for ongoing daily monitoring, which offers the highest predictive accuracy (AUC 0.88-0.93) among all scoring systems. 1, 2, 5
• Measure CRP on day 3; levels ≥150 mg/L indicate severe disease. 2, 5

Days 3-10:

• Perform contrast-enhanced CT with CT Severity Index (CTSI) calculation in all patients with predicted severe disease (BISAP ≥2, Ranson ≥3, or APACHE-II ≥8). 1, 2, 6
• CTSI ≥3 indicates severe disease; scores 7-10 correlate with 92% morbidity and 17% mortality. 2

Management Decisions Based on Scoring

BISAP ≥2 or Ranson ≥3 mandates:

• Immediate consideration for ICU or intermediate-care unit admission. 6, 5
• Aggressive fluid resuscitation and close monitoring for organ failure development. 6
• Contrast-enhanced CT between days 3-10 to assess necrosis extent. 2, 6, 5

Do NOT initiate prophylactic antibiotics based on severity scores alone (Grade 1A evidence). 1, 6

• Prophylactic antibiotics provide no mortality or morbidity benefit in sterile necrosis. 1
• Reserve antibiotics for documented infected necrosis only. 1, 6

Common Pitfalls to Avoid

• Do not wait 48 hours to escalate care in patients with high BISAP scores or clear clinical severity. The delay inherent to Ranson scoring can be dangerous. 6, 5
• Do not rely on Ranson score alone for ICU triage decisions. Combine with clinical organ-failure assessment and early BISAP scoring. 6, 5
• Recognize that Ranson's modest positive predictive value means many "severe" patients will recover uneventfully, but this should not deter appropriate escalation of care. 1, 2
• Continuously monitor for organ failure development, as its presence definitively defines severe disease and supersedes all scoring systems. 2, 6, 5